江豚的微笑 (作者︰洪家耀) The Smile of the Finless Porpoise (Author: Samuel Hung) by 香港自然探索學會 Society of HK Nature Explorers

江豚 e l i Sm

The

e s i o p r o P s s

e h t of

e l n i F 的

洪家耀 Samuel Hung

江豚的 The

Smile

of the Finless 洪家耀

Samuel Hung

Porpoise

序 Foreword

很

多朋友同儕曾問我，最喜愛哪個品種的鯨豚？我會

hen people ask me what my favourite cetacean species is, I can give them a straight answer

不假思索而肯定地答︰

right away: finless porpoise! They are

「江豚」﹗這時他們的頭上大多會出

usually quite puzzled with my answer, as

現很多的問號……

they would think that my favourite would be the charismatic Chinese white dolphins.

喜愛江豚的原因很多。對我來說，江

There are too many reasons to adore these

豚是一種神秘的動物，差不多是世界

little porpoises, and here I mention a few.

上最難研究的鯨豚品種，這令研究此動物的工作更具挑戰性。另外，江豚出現時的行為比中華白海豚低調得

Finless porpoises are such mysterious animals in our sea that they are probably one of the most challenging cetacean species to be studied around the world. I just love to take up this challenge! Also, our porpoises

多，驚鴻一瞥已能令我有難以言喻的

enjoy a much lower profile than the Chinese

滿足感。而且因大眾普遍忽略了江

white dolphins, and it is always satisfying

豚，令我想要「鋤強扶弱」(但我也要事先聲明，我其實也十分鍾情於中華白海豚啊﹗)，對牠們更為憐惜。

to just have a glance of their presence. It is also human nature to help raise awareness about these animals that are largely ignored by most people (but I also have to admit that I adore the Chinese white dolphins as well!).

再者，研究了江豚逾十多載，發現牠

Moreover, after studying them for over a

們的生活多姿多彩，個性十分活潑可

decade, I started to appreciate the interesting

愛，以前對牠們的誤解亦一掃而空。繼多年前編寫了一本有關中華白海豚

life of the porpoises. They are indeed very cute animals and have many intriguing behaviours. Once I get to know them more in the past decade or so, I cannot help but

的專書後，我亦深覺是時候為江豚做

fall in love with these porpoises.

一點事情，令香港市民更認識這種本

After writing a book on Chinese white

應與中華白海豚有同樣地位的鯨豚動

dolphins a number of years ago, I feel that

物。另一激發我撰寫此書的原因，就

now it is time for the finless porpoises, so that the Hong Kong public can get to know

是深覺江豚以往的生活環境較中華白

more about this cetacean that should also

海豚寧靜，人為活動也較少；但此情

enjoy some of the same attention received

況卻已正在不斷改變。面對愈發頻繁

by our lovely pink dolphins. Another

的高速船往來，海水污染、漁網誤捕等困擾江豚的嚴重問題，再加上越來

reason that prompted me to write this book is that the living habitat of finless porpoises has been deteriorating so there

越多沿岸發展工程，令香港的江豚失

is an urgent need to speak up about their

去一些賴以為生的安樂窩。我實在不

plight. They are facing heavier vessel traffic

能自已，感到必須為我鍾愛的江豚發

in their important habitats, problems of water pollution, incidental entanglement in

聲，與大眾分享牠們的生活點滴，及

fishing nets and impending further coastal

面對的困境，讓香港市民重新認識保

development projects that will cause acoustic

護牠們的重要。

disturbance and direct habitat loss. I feel a strong urge to share with you my concerns about their future survival in Hong Kong

此書能順利出版，實有賴各方好友協

waters. It is time for us to act now before

助完成。首先，要感謝兩位在江豚研

they disappear from our waters.

究領域上舉足輕重的人物 ~ 王愈超

There are many people that I need to

博士及解斐生博士，是他們令我深入

express my gratitude for their assistance

認識江豚，並啟發我進行研究江豚的工作。他們在過去十多年的指導，令我獲益良多。我亦感謝他們仔細鑒定此書的內容，並提供珍貴的相片。另外，亦要多謝過去多年以來跟我一起研究江豚的助理及實習生(包括為此書進行校對的內子及好友Theresa)；作者處理一條剛擱淺的江豚屍體 (攝於2003年2月) The author was investigating a freshly stranded finless porpoise (photo taken in February 2003)

with this book project and our finless porpoise research. First, I want to thank my two exceptional colleagues in cetacean science, Drs. John Wang and Tom Jefferson, for their dedication to finless porpoise research that has aroused my research interest towards this species.

Their

guidance and

他們常在日曬雨淋的情況下「海陸空地毯式搜索」江豚的蹤影，為研

encouragement in the past decade are integral to my research work on finless porpoises. They have also kindly provided help in this

究江豚工作作出重要的貢獻。由於

book’s editing as well as contributing many

他們人數眾多，我不能在此向他們

pictures for this book. There are so numerous

一一致謝，但我仍要向他們表達由

research assistants and research interns (including my wife and good friend Theresa

衷的感謝。不能不提的是，要感謝

that also helped proofread the contents of this

與我們在海上合作了十多年的船家

book) who assisted in our long-term research

吳志明夫婦，他們全力配合我們進行船上調查，對我們的長期鯨豚研究工作至為重要，而我亦常常心裡

on local finless porpoises. Although I cannot name them all here, I am always grateful for their dedication and diligent support for the local cetacean research programme, especially their willingness to meet the challenge in

為吳太對江豚出現的超級靈敏度而

searching for these elusive porpoises. Our

欣喜﹗

boat drivers, Mr. and Mrs. Ng Chi Ming, are

最後，我亦希望把此江豚小書，獻

porpoise research, as they always know how

給我心目中在中國鯨豚研究界裡的一位巨人 ~ 王丕烈教授。他一生數十載為中國鯨豚研究工作、尤其是在江豚研究方面貢獻良多。而他在艱辛的歲月裡，仍鍥而不捨地進行

critical to our success in local dolphin and to get things done for us at sea. As a side note, I am always impressed with the super sensitivity of Mrs. Ng to the occurrence of her beloved porpoises! Finally, I want to dedicate this book to the pioneer of cetacean research in China, Professor Peilie Wang. His life-long

研究和發表文章，更在過往多年不

contribution to cetacean science in China,

斷提攜後輩並加以協助。這位慈祥

especially on finless porpoises, laid an

的老教授，實在是我們一眾後輩的典範。王教授雖然現在已經退休多年，但我相信他必能啟迪更多後輩

important foundation for many young researchers to follow including myself. I always admire his dedication to cetacean research and his publications on a variety of topics, and most importantly his assistance

跟隨他的腳蹤，繼續為研究及保育

and advice to many young researchers

中國鯨豚而努力。在此謹祝王老師

throughout his life. I sincerely wish

生活愉快﹗

Professor Wang and his family the best, and hope that he will continue to support our research work!

目錄 Table of Contents 引言

Introduction

什麼是鼠海豚？

What are porpoises?

兩種江豚

Two species of Finless Porpoises

江豚在香港的歷史

Their history in HK

研究員如何研究江豚

How do researchers study them?

江豚在香港的情況

Their status in HK

江豚的行為

Their behaviours

江豚的一生

Their life history

江豚面對的威脅

Their existing threats

江豚的將來

Their future

引言 Introduction

在

香港，「中華白海豚」可算是一個家傳戶曉的名字。

在過去十多年來，很多香港人已在大嶼山見過牠們的廬山真面目，或在電視得知牠們的最新動態。白海豚的知名在香港只有很少市民曾一睹江豚的廬山真面目

程度，令牠們成為香港的動物明星、旗艦物種。但在芸芸十七種曾經在香港出現過的鯨豚物種中，其實

Only a few people in Hong Kong have had a glimpse of the mysterious finless porpoises

還有另一種跟白海豚一般，都是長居香港的「原居民」，但牠們卻普遍為香港人忽略。牠們的性格害羞，不太好動，從未有人見過牠們跳出水面，而且其體色亦不如粉紅色的中華白海豚般搶眼，所以極難在海上發現牠們的蹤影。雖然牠們的魅力遠不及中華白海豚，但其實兩者均在香港海洋生態扮演重要的角色；事實上，兩者亦有不少相同之處。當大家有機會認識這種有趣可愛的生物時，必定會愛上牠們，並希望保護牠們。我們希望藉這本小書，揭開牠們神秘的面紗，並詳盡介紹這種長年居住香港的海洋生物。牠們是誰？就是這本書的主角 ~

江豚﹗

he Chinese white dolphin has been a household name in Hong Kong for over a

decade, and many locals have seen them around Lantau Island or have heard about them in the news. Their popularity has resulted in them being the “flagship species” or “animal icon” for Hong Kong’s marine environment. Amongst the 17 species of cetaceans that have been recorded in Hong Kong, there are two resident species that live here all year. In addition to the Chinese white dolphin, there is another resident cetacean in our waters that has been largely overlooked by the Hong Kong public. They are very shy and difficult to observe at sea. They are not acrobatic, so no one ever sees them leaping out of the water, and they don’t have the attractive pink colour of the Chinese white dolphins. Even though they are not as charismatic as our pink dolphins, they are nevertheless an important part of our marine ecosystem and share many similar characteristics with the dolphins. And once people start to learn more about them, they are sure to fall in love with these adorable creatures and will want to protect them as well! And that’s the purpose of this booklet, to introduce to you these mysterious creatures that have inhabited Hong Kong waters for thousands of years. So, who are they? Our mysterious and elusive

finless porpoises!

什麼是鼠海豚？ What are porpoises?

Cetaceans, including all whales, dolphins and porpoises, are air-breathing mammals that spend their entire lives in the water. They share the same characteristics of all mammals, such as

鯨豚動物包括所有鯨魚、海豚及鼠海豚，是哺乳類動物的成員，並與其他哺乳類動物一樣是胎生動物、會用乳汁哺育幼兒、及用肺呼吸。由於牠們全時間生活在海洋中，鯨豚動物在進化過程中發展出各種有趣的適應能力。例如，牠們有厚厚的皮下脂肪以保持恆溫(在熱帶居住的鯨豚，如江豚及中華白海豚等的皮下脂肪一般較薄)；擁有流線形的身軀以減少在水中游動時所產生的阻力；而且擁有高效能的肺部，以最有效的方法貯藏及使用體內的氧氣，才能在水中閉氣良久。

giving birth to live young, nursing their young with milk, and breathing air with lungs. But in order to cope with the many challenges of living in the marine environment full-time, these mammals have also evolved many interesting adaptations. For example, all cetaceans have a thick layer of blubber (i.e. fat layer) underneath the skin to keep warm (though in general, tropical species such as finless porpoises and Chinese white dolphins have a thinner blubber layer); a streamlined body to reduce drag when moving through the water column; and the lungs are very efficient in air exchange in order to be able to stay submerged underwater for an extended period.

江豚擁有哺乳類動物的特徵，在此擱淺個體的腹部近肛門及生殖裂兩側的乳腺就是用來哺育幼兒。 Finless porpoise bears all the characteristics of a mammalian species. Mammary slits used for nursing young with milk can be found on the two sides of the anus and genital slit from the ventral region of this stranded specimen.

中華白海豚 Chinese white dolphins

江豚 Finless porpoises

鯨豚動物可分為鬚鯨及齒鯨兩大類，而齒鯨則可再細分為十個科。中華白海豚 (或稱印度太平洋駝背豚) 是海豚科的成員，而江豚則屬於鼠海豚科。所以，香港兩種本地鯨豚在分類上的關係其實不是太大，因此牠們無論在外形上，抑或其生態特徵上均存在很多差異。 Cetaceans can be divided into two main groups: baleen whales (suborder Mysticeti) and toothed whales (suborder Odontoceti). There are a total of 10 families under the group of toothed whales. For example, Chinese white dolphins (also known as the Indo-Pacific humpback dolphins) belong to the Family Delphinidae, or the dolphin family, while finless porpoises belong to the Family Phocoenidae, or the true porpoise family. Therefore, our two resident species are actually not that closely related, and they have some major differences in their morphology as well as ecology.

由於中華白海豚和江豚在分類上沒有太大關係，所以其外形亦截然不同。 The Chinese white dolphins and finless porpoises are not closely related at all, and their external appearances are also drastically different.

究竟海豚跟鼠海豚有什麼不同呢？一般來說，鼠海豚的體形較為細小，牠們的體長一般不會超過2.5米；牠們沒有海豚科成員所擁有長長的吻部；除了白腰鼠海豚以外，所有鼠海豚科成員的背鰭前方邊緣均有一些突起的小突粒 (江豚的小突粒可在背脊上找到)；而牠們最明顯的分別，就是牙齒的形狀。鼠海豚科成員的牙齒都是鏟形的，而海豚科成員的牙齒則呈圓錐形。 So, what’s the difference between a dolphin and a porpoise? Well, porpoises are generally smaller in size, and no member of the family exceeds 2.5 m in body length. They all lack the long rostrum, which is a common characteristic of most members of the dolphin family. Moreover, besides the Dall’s porpoise, all members of the porpoise family have epidermal tubercles (or small hard bumps) lining

從空中觀察香港江豚的背部，可見到背脊上一行行的小突粒。 An aerial view of the dorsal region of a finless porpoise in Hong Kong shows a series of tubercles lining along its dorsal ridge.

鼠海豚 porpoise

海豚 dolphin

along the leading edge of the dorsal fin (or dorsal ridge in the case of finless porpoises). Finally, probably the most prominent feature to distinguish a porpoise from other toothed whales is found with their teeth. Members of the porpoise family have spade-shaped teeth unlike the teeth of their distantlyrelated dolphin cousins, which are conical.

呈圓錐形的海豚牙齒與呈鏟形的鼠海豚牙齒，可作為區分這兩種動物的最明顯特徵。 The cone-shape teeth of dolphin and spade-shaped teeth of porpoise are the most prominent features to tell the two apart.

鼠海豚科內的七個成員，均有一些相同的生態及行為特徵。譬如說，與海豚相比較，鼠海豚在出生後頭數年的成長較急速，並在較小的歲數已達性成熟。有些鼠海豚科成員更能每年繁殖下一代，即是說一些雌性能同時哺乳及懷孕。另外，過去

鼠海豚科成員的壽命大多被低估；圖為一被漁網誤捕的港灣鼠海豚。 The longevity of most porpoises were underestimated in the past; this picture shows a bycaught harbour porpoise.

的研究均發現鼠海豚一般壽命較短，只有少數能活超過20歲；但有些專家則認為鼠海豚短壽的說法可能並不完全正確，因為過去有關鼠海豚壽命研究樣本主要來自一些受漁業誤捕威脅的種群，所以牠們可能未能存活至老年就已經死去。還有，除了白腰鼠海豚會在船首躍浪以外，其餘鼠海豚科成員都極為害羞及「神出鬼沒」，牠們大多只會在水面快速滾動，所以在野外觀察牠們十分艱難。

The seven members of the porpoise family also share other similar features in their ecology and behaviour. For example, when compared to dolphins, porpoises grow very rapidly in their first few years and attain sexual maturity at an earlier age. Some porpoises are even capable of reproducing annually, which means some females are capable of lactating while being pregnant at the same time. Most porpoises have relatively short life spans and few are known to live longer than about 20 years. However, that dataset could be biased because most of the porpoises that have been aged died prematurely as a result of fishery interactions, so these porpoises were not able to reach their maximum age. Finally, with the exception of the Dall’s porpoises, which are known to bow ride, all other species of porpoises are very shy and cryptic animals. They typically roll quickly at the water surface, which makes it very challenging to see and follow them at sea.

鼠海豚大多是神出鬼沒的動物；圖為加拿大芬地灣出現的港灣鼠海豚。 Most porpoises are cryptic and elusive animals; this picture shows a harbour porpoise occurring in the Bay of Fundy, Canada.

在往後的數章節中，我們將詳盡介紹兩種江豚，但現在讓我們先來認識一下鼠海豚科其餘五位成員的一些有趣資料吧﹗ Besides the Indo-Pacific and narrow-ridged finless porpoises which will be described in greater detail in the following chapters, here is a quick glance at some interesting facts about the other members of

the porpoise family:

加灣鼠海豚 Vaquita ( Phocoena sinus ) 除了被認定為「功能性滅絕」的白鱀豚

Live vaquita photos taken under permit (Oficio No. DR/488/08) from the Secretaria de Medio Ambiente y Recursos Naturales (SEMARNAT), within a natural protected area subject to special management and decreed as such by the Mexican Government.

外，加灣鼠海豚相信是世界上最瀕危的鯨豚品種。此品種的分佈範圍極其狹窄，只會在墨西哥加利福尼亞灣的北端出沒。在鼠海豚科裡，加灣鼠海豚是體形最細小的一員，而牠們外形上最明顯的特徵就是其大大的「黑眼圈」及黑色的「嘴唇印」。鼠海豚被世界自然保育聯盟列為「極度瀕危」的品種，牠們的數目在近數十年內大幅下降，主因是牠們經常被當地水域的流刺網纏繞致死。 Besides the baiji, which has been determined to be functionally extinct, the vaquita is the most endangered species of cetacean in the world. The distribution of the entire species is very limited, only occurring in the upper Gulf of California, Mexico. They are the smallest of all porpoises, and their most prominent feature is their pigmentation with relatively large black eye rings and lip patches. The vaquita is listed as a Critically Endangered species under the IUCN Red List. The reason for this status is mainly the frequent entanglements by gillnet fisheries, which has caused a significant decline in their numbers.

港灣鼠海豚 Harbour porpoise ( Phocoena phocoena )

此品種廣泛分佈於北太平洋、北大西洋及黑海的溫帶，以及靠近北極近岸水域，亦應是鼠海豚科中數量中最多的品種。可惜的是，港灣鼠海豚亦深受漁網誤捕所威脅，令牠們在一些水域的情況岌岌可危。 This species is widely distributed in the coastal temperate to subpolar waters of the North Pacific, the North Atlantic and the Black Sea, and is likely the most abundant among all members of the porpoise family. Incidental catches of this species, primarily by various types of gillnets, throughout its range are high, and this is likely the most significant threat to their survival in many places.

白腰鼠海豚 Dall's porpoise ( Phocoenoides dalli ) 牠們是一種生活於寒冷水域的品種，主要分佈在北太平洋、毗鄰的白令海、鄂霍次克海及日本海。牠們的外形十分搶眼，擁有純白色的肚皮及黑色粗壯的身軀。牠們游動迅速，活潑好動，亦是唯一一種會乘船首躍浪的鼠海豚！在日本水域，白腰鼠海豚常被漁民以魚叉捕捉作食物，而各地的白腰鼠海豚亦不時被各樣漁具纏繞致死。 This is a cold-water porpoise species that can be found in the North Pacific Ocean and the adjacent Bering, Okhotsk and Japan seas. Their diagnostic feature is quite distinctive: a black robust body with a large, ventrally continuous white patch on the belly and sides. They are very fast swimming and active animals, and are the only porpoise species that is known to bow-ride. Dall’s porpoises are hunted by hand harpoons in Japanese waters for human consumption, and they are also taken incidentally by various net fisheries throughout their range.

棘鰭鼠海豚 Burmeister's porpoise ( Phocoena spinipinnis ) 此品種只於在南美洲的東岸及西岸出沒，主要分佈於近岸及較淺水的水域。此品種名稱其實來自其背鰭上找到的「棘刺」。另一明顯的特徵就是位於身軀較後位置的背鰭，這與其他小型鯨豚明顯不同。鯨豚專家對棘鰭鼠海豚的生態及行為所知甚少，只知道牠們會在秘魯、智利及阿根廷等水域被漁網誤捕。 This porpoise species can only be found on the east and west coasts of South America, mainly inhabiting coastal waters that are fairly shallow. Its scientific name Phocoena spinipinnis (“spiny porpoise”) refers to the distinct tubercles (little bumps) that are present on its dorsal fin. Another diagnostic feature is the triangular dorsal fin, which is situated quite far back on the body. Very little is known about the ecology and behaviour of Burmeister’s porpoise, but they are known to be taken by fisheries in Peru, Chile and Argentina.

黑眶鼠海豚 Spectacled porpoise ( Phocoena dioptrica ) 此品種只在南半球的溫帶、亞南極及南極水域出沒，是世界上最鮮為人知的鯨豚動物。牠們身體顏色極不尋常，成年雄性更擁有特大背鰭，令人很容易就可在海中辨認出這品種。極少人在海中遇見過黑眶鼠海豚，有關牠們的生物資料主要來自擱淺的屍體。由於人類對牠們的生物資料掌握甚少，令保育牠們的工作變得十分困難。 This species has a circumpolar distribution in temperate, subAntarctic, and Antarctic waters, and is one of the most poorlyknown cetacean species. They can be readily identified by their unusual pigmentation, and the strikingly large dorsal fin exhibited by mature males. Spectacled porpoises have been rarely sighted at sea and most of the information about this species has come from stranding events. Unfortunately, the biological information needed for conservation and management of this species is unavailable.

兩種江豚 Two species of Finless Porpoises

印度太平洋江豚 Indo-Pacific finless porpoise ( Neophocaena phocaenoides )

於香港擱淺的印度太平洋江豚 A stranded Indo-Pacific finless porpoise found in Hong Kong

生活在長江自然保護區的窄脊江豚 A narrow-ridged finless porpoise living in a nature reserve along the Yangtze River

在日本水域被拯救後作人工馴養的窄脊江豚 A narrow-ridged finless porpoise kept in captivity at a Japanese aquarium that was originally rescued from local water

窄脊江豚 Narrow-ridged finless porpoise ( Neophocaena asiaeorientalis )

根據最新的遺傳基因研究，江豚此品種現在被一分為二，即「印度太平洋江豚」及「窄脊江豚」。從兩者的外形上來看，兩種江豚的主要分別在於牠們的背部形態：「印度太平洋江

這兩條印度太平洋江豚出現在馬來西亞的一個紅樹林區附近 Two Indo-Pacific finless porpoises near mangrove swamps in Peninsular Malaysia

豚」的背寬而平，背上有為數10-25行的小突粒，小突粒範圍寬約48-120毫米。而「窄脊江豚」則有高達5.5厘米的隆脊，其上只有1-5行的小突粒，小突粒範圍通常不超過30毫米寬。有趣的是，「印度太平洋江豚」在年少時呈淺灰色，待年紀漸長時體色逐漸變深；但「窄脊江豚」在日本水域的亞種卻剛好相反，牠們出生時為深灰色，但成年的時候卻逐漸變成淺灰色至奶白色。由於日本江豚的體色與眾不同，牠們會否成為一獨立江豚品種仍有待研究。事實上，在分類學上江豚跟中華白海豚同樣極為複雜，此研究領域亦急需研究員不斷加以探索，以提供重要的資料，讓相關人員了解保育這些珍貴鯨豚的迫切性。

Thanks to recent solid genetic evidence, finless porpoises are currently divided into two species: the Indo-Pacific finless porpoise (Neophocaena

phocaenoides ) and narrow-ridged finless porpoise (Neophocaena

asiaeorientalis ). From the external morphology, the two species of finless porpoises can be readily distinguished by the appearance of their dorsal surfaces. The Indo-Pacific species is characterized by a low and wide area of tubercles (about 48-120 mm in width) which is lined with 10-25 rows of these little bumps. The narrow-ridged species has a distinct and narrow dorsal ridge (less than 30 mm in width) that can be up to 5.5 cm high and lined with only 1-5 longitudinal rows of tubercles. Interestingly, the Indo-Pacific finless porpoises are light gray in colour when they are young, and become darker as they age. However, a subspecies of narrow-ridged finless porpoises that lives in Japanese waters are dark gray in colour when they are first born, and become light gray to creamy white in colour when they become adults. It will be interesting to see whether these Japanese finless porpoises will eventually become another species of finless porpoise given their unique pigmentation. Overall, the taxonomy of finless porpoises seems to be as complicated as that of the Chinese white dolphins. It is an interesting topic for scientists to explore and such information will be important to wildlife managers when trying to understand the conservation status of these cetaceans.

上述兩種江豚品種只會在亞洲水域出現；「印度太平洋江豚」較常在熱帶水域水出沒，分佈範圍包括印度洋及南中國海水域，而「窄脊江豚」則主要在東亞地區較寒冷的溫帶水域出沒。這兩種江豚主要都在近岸水域生活，當中包括較淺水的海灣、紅樹林區、河口及一些主要河流。雖然牠們普遍較喜愛在鹹淡水交界的河口環境出現，但在香港的情況卻正好相反；香港江豚大多在鹽度較高的水域出沒，但卻不曾出沒於鄰近的河口環境 (即珠江口)。 Both species of finless porpoises only occur in Asian waters. The Indo-Pacific species is in general the more tropical of the two species being distributed from the Indian Ocean to southern Chinese waters, while the narrow-ridged species is found in temperate to cold temperate waters in East Asia. Throughout the distribution of both species, finless porpoises occur mainly in coastal waters, including shallow bays, mangrove swamps, estuaries and in some large rivers. They also appear to prefer estuarine waters in many parts of their ranges but the ones in Hong Kong appear to be an exception, occurring in oceanic saline waters rather than brackish waters.

一條在馬祖群島水域被漁網誤捕的窄脊江豚屍體 A narrow-ridge finless porpoise that was caught incidentally by local fishermen in the waters of the Matsu Islands

再仔細看看，「印度太平洋江豚」廣泛分佈於印度洋及太平洋西岸，西至波斯灣、東南至印尼、東北至台灣海峽及中國中部海域。相比下，「窄脊江豚」分佈由南面的台灣海峽起，至中國北部及韓國的黃海、渤海，再向北伸延至日本中部水域。值得一提的是，「窄脊江豚」其中一亞種居於中國長江流域，分佈由河口一直伸延至上流1,600公里。此兩種江豚的唯一分佈重疊地方，就是位於台灣海峽中部；將江豚品種一分為二的分類研究就是在此重疊區採樣。而在這地區的馬祖群島 (由台灣政府管轄) 是唯一可同時在野外觀察到兩種江豚的地方。

生活在長江的窄脊江豚

More specifically, the Indo-Pacific finless porpoise

A narrow-ridged finless porpoise that lives along the Yangtze River

ranges around the rim of the Indian Ocean and the western Pacific Ocean, from the Persian Gulf in the west, to Indonesia in the southeast, and

to the Taiwan Strait and central Chinese waters in the northeast. In comparison, the narrow-ridged finless porpoise ranges from the Taiwan Strait to Bohai and Yellow Sea of China and Korea, and to central Japanese waters in the north. There is also a subspecies of narrow-ridged finless porpoise that is believed to occur only in the Yangtze River of China, where it ranges up to 1,600 km upstream from the river mouth. It is also interesting to note that an area of sympatry, where both species occur, is found in the Taiwan Strait, where research was conducted to separate the two species. In the waters of the Matsu Islands (Taiwan) both species of finless porpoises can be reliably observed.

江豚在香港的歷史 Their history in HK 香港人大多都不知道江豚的存在，這相信跟江豚怕人的性格有關，因而令人難以觀察牠們。事實上，雖然漁農自然護理署(漁護署)在過去多年搜集了不少江豚的擱淺資料，但直至過去十多年間我們才開始慢慢認識牠們，而這些知識主要來自在1998年漁護署資助、針對江豚種群生物學的深入研究。這項長期監察江豚的研究仍在進行中，這本小書所介紹的江豚資料正正是這些研究的珍貴成果。 Most people in Hong Kong are not aware of the existence of local finless porpoises. This general lack of awareness is mainly due to the porpoises’ cryptic behaviour at sea, which makes them extremely challenging to observe from a boat. In fact, there have been many records of stranded porpoises since the Agriculture, Fisheries and Conservation Department (AFCD) started to collate information on cetacean stranding events, but our understanding about them has been poor until fairly recently. In 1998, AFCD funded a comprehensive research study to investigate various aspects of population biology of finless porpoises in Hong Kong. As a result, our knowledge about the local porpoises has grown significantly in the past decade. The research on this mysterious sea creature in our waters is still on-going and what you are about to learn here are the fruitful results of this long-term study.

香港政府部門漁農自然護理署在多年來搜集江豚擱淺的資料 The Agriculture, Fisheries and Conservation Department of Hong Kong SAR Government has collected information from stranded finless porpoises for many years

在西貢清水灣天后廟旁發現的一個江豚頭骨 A finless porpoise skull found at a Tin Hau Temple near Clearwater Bay, Sai Kung

雖然香港人大多不認識江豚，但本地漁民卻一直知道牠們的存在。漁民不會視江豚如中華白

Even though most people do not know

海豚般般神聖。如果不小心捉

anything about finless porpoises, fishermen

到牠們的話，有些漁民更會吃掉

have been observing them for generations.

牠們﹗本地漁民一般稱呼江豚為

The fishermen do not regard finless porpoises as positively as the Chinese white dolphins,

「海豬」，在海中遇見牠們時，

and some would even eat porpoises if they

更親切地叫江豚作「豬仔」。有

caught them. In fact, a nickname given to the

些漁民透露，由於江豚有厚厚的皮下脂肪，所以牠們的肉可給製成臘肉。但當然，會這樣做的漁

finless porpoise by fishermen is “sea pig”, and when fishermen see porpoises, they will usually call them “little pigs”. Some fishermen have even mentioned that porpoise meat has been made into preserved meat, probably

民為數不多。漁民一般不會主動

because of their oily blubber layer, but these

捕捉江豚，即使不小心誤捕牠們

fishermen are likely the minority. It is unlikely

時，亦會快快地將屍體扔回海中，以免招來惡運。研究員近年亦在一些本地的天后廟發現江豚

that fishermen hunt for porpoises deliberately, and most often they will just discard porpoises that have been caught incidentally back into the sea. It is also interesting to note that even though most fishermen do not consider the

的頭骨，所以有理由相信，雖然

finless porpoise as a sacred creature, like the

漁民不會視江豚為神靈的化身，

Chinese white dolphin, the skulls of porpoises

但在傳統信仰上還是對牠們抱著一點敬畏的。

were occasionally brought back to Tin Hau Temple in Hong Kong, probably for religious purpose.

研究員如何研究江豚 How do researchers study them? 香港的鯨豚專家已研究江豚超過十年，為了揭開牠們神秘的面紗，研究員用了不同的研究方法，希望了解牠們在香港生活的狀況。為作近距離觀察，研究員定期於江豚的棲息水域進行船上調查，這種用作研究江豚數目及分佈的系統性專門方法，稱為「樣條線船上調查法」。基本上，研究員將香港廣闊的水域

研究員在定期的船上調查搜集江豚分佈及數目等資料 Researchers collecting data on distribution and abundance of local porpoises during regular line-transect vessel survey

劃分為十二個研究區，再在每一個區設定一些路線；每次進行調查時，研究員便會重複在這些特定路線航行，並在研究船上層尋找江豚的蹤影。在船上調查期間，研究員會搜集多項數據。其中環境狀況數據，是有效觀察江豚出沒的一重要因素，因為江豚在水面呼吸的動作十分短促，所以在海面狀況較差的情況下，會較難找到牠們。

Local researchers have been studying finless porpoises for over a decade now. In order to have a peek at the life of these mysterious creatures, several research methods have been employed. To observe finless porpoises up close, researchers conduct regular vessel surveys within the habitat of the porpoises. The systematic method used to study the distribution and abundance of local porpoises is called “line-transect survey method”. Basically, predefined routes are set in twelve survey blocks within Hong Kong territorial waters, and the research vessel would follow these routes repeatedly over time while researchers would look for porpoises on the upper deck of the survey vessel. During the course of the surveys, various data would be collected, including the environmental conditions, which can be a critical factor for sighting porpoises effectively. When porpoises come up for a quick breath of air, they usually roll quickly at the water surface making them a great challenge to find in even moderately rough sea conditions.

除了在海上用肉眼尋找江豚，研究員亦會利用聲納儀器搜集江豚發出的聲音訊號，這樣的話，即使研究員肉眼看不到江豚，也可知道研究船附近有沒有江豚。由於江豚十分害羞及較難觀察，水底聲納探測可協助研究員判斷在進行樣條線船上調查時未被發現的江豚比率。研究員就是利用一種特製的儀器 – 鼠海豚偵測器(POD) – 用作這類水底監察工作。鼠海豚偵測器是一個全自動系統，當江豚出現並發聲的時候，這種儀器會自動儲存牠們發出的一些超高頻率的卡嗒聲。

用以搜集江豚發聲數據的「鼠海豚偵測器」 The Porpoise Detector (POD) that was used to collect acoustic data from vocalizations of finless porpoises

While at sea, researchers have also studied the acoustic signals emitted by the porpoises, to determine their presence or absence even if not visible at the surface. Since porpoises are very shy and difficult to observe, acoustic detection can aid researchers in deducing how many porpoises may have been missed during the line-transect surveys. The POrpoise Detector (or POD) is a specialized acoustic equipment that was used in Hong Kong for this type of study. The POD is an automated system designed to “sense” the presence of porpoises by detecting very high-frequency “clicks” produced when porpoises vocalize.

江豚在海況較好的情況下較容易被發現 Finless porpoises can be detected and observed more easily during calm sea condition

除了在海上觀察外，本地研究員更會從陸地上及空中研究江豚的生活﹗為了解江豚的自然行為及使用一些「出沒熱點」的情況，研究員曾在索罟群島的大鴉洲、南大嶼山的貝澳、及南丫島的下尾咀設立陸上觀察點，以進行長時間的江豚搜索及觀察。此外，為了在一些較偏遠的水域(如香港東部水域和大鵬灣等)尋找江豚，研究員亦會利用經漁護署安排的政府飛行服務隊直升機，定期在空中調查江豚的分佈及行為。當江豚在水面活動時，研究員可從陸地及直升機等平台俯瞰觀察，所以這兩種江豚調

陸上觀察及直昇機調查均能有效地研究江豚的行為及分佈 Land-based observation and helicopter survey are both effective means to study the distribution and behaviour of finless porpoises

查方法比船上調查更為便利。事實上，由船上觀察到的江豚行為甚為沉悶，因為牠們只會在水面上重複滾動，看來不甚活躍，很多時更會在研究船接近時就遠遠躲開；但是從高空觀察江豚的行為，對牠們造成的滋擾較小，所以往往可以觀察到牠們的自然行為：牠們其實十分活潑好動，並花很多時間在水面附近活動。

從高空可觀察到整條江豚的身體及其自然行為 Observing finless porpoises from above can examine their full body an d th e i r natural behaviours

Besides observing them from sea, researchers in Hong Kong have also studied porpoises from land and from the air! In order to study their behaviour and usage of certain “hotspots”, researchers have set up several land-based observation stations at Tai A Chau, Pui O and Lamma Island to search for porpoises. Moreover, to look for porpoises in some remote areas, such as the eastern offshore

waters and Mirs Bay, local researchers also have the privilege of periodically using helicopters operated by the Government Flying Services (through the arrangement of the AFCD) to survey these areas. Since porpoises can be seen through the water surface from land and from air, when they are at or near the surface, it is much easier to find and observe them from above; than it is from across in a boat which is much lower in the water.

From a

boat, the porpoises can appear quite boring and inactive when they are seen just breaking the water surface in repeated rolls before making a dive. But observations from above have shown porpoises to be much more active and spend much of their time just below the water surface.

值得一提的是，香港研究員可憑中華白海豚身體上的各種特徵，包括背鰭上的切痕、身上的斑點圖案或明顯傷痕，用作辨認及區分不同的海豚個體，此方法名為「相片辨認法」；然而，此方法卻無法應用在江豚身上。這是因為江豚既沒有背鰭，身上又沒有任何鑑別特徵，再加上牠們害羞的性格，令研究員難以近距離觀察及拍攝，所以在過去的十多年來，研究員都未能可靠地辨認出江豚的個體。事實上，江豚在眾多鯨豚動物中，是極少數未能以「相片辨認法」研究的品種。不能辨認個體的問題亦大大限制了我們對江豚的認識，如牠們的移動模式及使用香港水域的情況，都是必須靠「相片辨認法」才能了解的範疇。 It should also be mentioned that one of the important research techniques used to study Chinese white dolphins in Hong Kong, cannot be used to study finless porpoises.

雖然研究員尚未成功辨認出一些江豚個體，但這數條均有一些明顯的潛在特徵以供辨認。 Although researchers have not been able to identify individual porpoise so far, these few porpoises do bear some unique features that can be potentially used as identification characteristics

For Chinese white dolphins, individuals can be identified by distinct features on their body, including the nicks and cuts along their dorsal fin, unique spotting patterns, or injury marks, a technique called photo-identification. However, since finless porpoises do not possess a dorsal fin, and are very difficult to approach, they cannot be identified individually. In fact, finless porpoises are two of the few cetacean species that cannot be identified individually. This shortcoming has greatly limited our knowledge of their movement and residency patterns and other important aspects of their population biology that we have come to understand for the Chinese white dolphins.

由於在海上觀察江豚極為艱辛，所以從中得到的資料也十分有限。有關江豚的研究員正為一條擱淺江豚屍體作仔細量度 External morphometrics of a stranded finless porpoise w e re ca re fu l l y measured by local researchers

生物資料，其實有很多都是來自擱淺的江豚屍體。研究擱江豚的首要目的，就是找出牠們的死因，所以研究員會先仔細檢查屍體，以找出一些重要的線索來確定死因，例如仔

細觀察江豚屍體的胸鰭及尾鰭，是否留下一些被漁網纏繞的痕跡。此外，研究員亦會仔細量度江豚各部位，用以研究其成長模式，及與其他江豚種群作分類學上的比較。研究員也會解剖江豚屍體，以收集一些樣本作化驗及檢查；例如，研究員可利用牠們胃部內的食物殘渣以了解其覓食習慣，利用其皮下脂肪及腎臟樣本作環境污染物分析，及利用牙齒鑑定擱淺江豚的年齡。由擱淺的江豚身上所得到的資料，可讓我們更深入認識牠們的生活細節﹗ Since porpoises are very difficult to observe in their habitat, much of the information about these species has actually come from stranded carcasses. The primary goal of investigating stranding events of porpoises is to find out their cause of death. To achieve this, their bodies are examined to determine whether there are any signs of injury, such as net marks

研究江豚骨骼結構是遺傳分類學上一種傳統的研究方法 Osteological examination of the skeleton of finless porpoise is a traditional method to study its taxonomy

around pectoral fins and flukes caused by fishing net entanglement. In addition, researchers measure the external morphometrics of local porpoises to study their growth pattern as well as to compare them with other porpoise populations in different areas for taxonomic purposes. Moreover, different tissue samples are usually collected for various studies: their stomach contents for feeding habitat analyses; blubber and kidney for environmental pollutant analysis; and teeth for aging. There is much information researchers can learn from dead porpoises that can never be gained from studying living ones!

江豚在香港的情況 Their status in HK 江豚一年四季都在香港水域出沒，可算是本地的原生品種。牠們主要在香港的南面及東面水域生活，但卻似乎迴避香港以西水域 - 即中華白海豚主要的出沒水域。雖然香港的海豚長期研究監察已進行了十多年，但研究員從未在大嶼山以西及以北水域發現過江豚。有趣的是，雖然中華白海江豚與中華白海豚在香港水域裡從不碰頭

豚及江豚的生活範圍在香港某些水域有重疊，但研究員從未曾在這些區域見過此兩品種同時出現。為何江豚好像永遠要避開中華白海豚主要出沒的生境呢？此獨特的生境分隔的背後

Finless porpoises and Chinese white dolphins appear to avoid each other in Hong Kong waters

原因，對香港鯨豚研究員來說仍然是一個謎。一些研究員認為，江豚及中華白海豚在食物資源上可能存在著一些競爭；有些則估計兩者之間或出現一些具侵略性的行為，而這些行為可能是身體上的碰撞、或利用聲音對對方作出一些滋擾；另有說法認為江豚在香港的分佈主要跟牠們繁殖的時間及由珠江排出的淡水量有關；最後的說法看來較為合理，所以在此再作深入探討… 江豚在香港的分佈呈明顯的季節性變化︰在冬春兩季，牠們較多出現在南大嶼山及南丫島一帶水域，而且數量較多；而在夏秋兩季，江豚卻絕跡於這片水域，轉而在香港東面水域出沒。研究員亦察覺到，香港江豚的繁殖季節主要集中在每年十月至翌年一月期間，而在大嶼山南及南丫島進行陸上觀察，也可常在近岸水域見到江豚母子出沒。有理由相信，江豚可能需要在繁殖期游到較遮蔽及食物資源較豐富的近岸水域哺育幼豚。這正可解釋為何牠們只在冬春兩季於香港南部水域出沒。總而言之，繁殖期的季節性變化可能是香港江豚在特定時間進出香港南面水域的重要原因，而且江豚亦可能趁中華白海豚在冬春兩季離開大嶼山南面水域時進佔使用。

In Hong Kong, finless porpoises can be found year-round and are considered a resident species. Porpoises mainly occur in the southern and eastern waters of Hong Kong, and largely avoid the western waters where Chinese white dolphins are found. In fact, researchers have never seen a single porpoise to the north and west of Lantau. It is interesting to note that the range of finless porpoises does overlap with that of Chinese white dolphins in some areas, but the two species have never been seen interacting with each other. So why do porpoises appear to avoid the prime habitat of the dolphins, and why do they never interact with each other? The driving force of this “habitat partitioning” is still a mystery to local researchers. Some suggest that dolphins and porpoises may be competing with each other over food resources. Others have even speculated that aggressive behaviour (either physical or acoustic) may take place between the two species. Another plausible explanation may be related to the timing of when porpoises reproduce and freshwater outflow volume of the Pearl River. What does that mean? Porpoises in Hong Kong exhibit distinct seasonal

江豚母子大多於冬春兩季在香港南面水域出沒 Mother and calf pairs of finless porpoises are often observed in southern waters of Hong Kong during winter and spring months

variation in their distribution. They are most abundant during winter and spring months, when they mainly occur in South Lantau and Lamma waters. Then porpoises will mostly disappear from these waters in summer and autumn months, while porpoise occurrence tends to increase in eastern waters during these months. Researchers noticed that porpoises in Hong Kong showed distinct reproductive seasonality

with most births estimated to occur between October and January. Observations from land also revealed that more mother-calf pairs can be found closer to shore during the months when they mainly occurred in South Lantau and Lamma. Therefore, porpoises may be moving to inshore waters during their calving season to find sheltered bays with abundant food resources while nursing their young. The timing of the reproductive cycle of porpoises may explain why their density is much higher during winter and spring months in South Lantau and Lamma. To sum it up, reproductive seasonality of porpoises could be the main driving force for their seasonal movement in and out of the southern waters of Hong Kong during certain months of the year. The porpoises may also have such seasonal shifts to take advantage of Chinese white dolphins moving out of these southern waters when the influence of the Pearl River becomes insignificant there.

在香港較常發現江豚蹤影的一些水域看過江豚在香港的整體分佈後，我們再細看牠們會否偏愛某類生境。經過詳盡的棲身地運用分析，研究員發現江豚的密度明顯地在大鴉洲 ( 索罟群島南面的島嶼)、石鼓洲、長洲、南丫島西南角、蒲台島一帶水域較高。這些水域均有一些類

貝澳灣及石鼓洲 Pui O Wan and Shek Kwu Chau

似的特質，例如均集中在島嶼附近、有較傾斜的海床坡

索罟群島

度(即水深差別較大)、及遠

Soko Islands

離人類活動 ( 如船隻或漁船經常經過 ) 的地方。雖然研究員對江豚的生境要求還未能完全掌握，但可以肯定以上的水域都是牠們的主要生境，必須加以保護，以防受到人為活動及沿岸發展所破壞﹗

A few porpoise “hotspots” in Hong Kong

Besides the general distribution pattern in Hong Kong waters, finless porpoises seem to exhibit some preference for certain areas as their prime habitat or hotspots. For example, from a detailed analysis of porpoise habitat use, it was shown that porpoise densities were particularly high near Tai A Chau (the southern most island of the Soko Islands),

南丫島 Lamma Island

Shek Kwu Chau, Cheung Chau, near the southwest corner of Lamma Island, and around the Po Toi Islands. These favourite

蒲台群島之橫瀾島

spots for the porpoises all share

Waglan Island of Po Toi Islands

similar habitat characteristics: they are usually located around an island, with steep seabed gradients nearby (or great dropoffs in water depth), and areas without much human activities, such as vessel traffic or fishing activities. Although the habitat requirements of porpoises are not fully understood, these hotspots can all be considered important porpoise habitats that should be safeguarded from anthropogenic activities including coastal development!

透過樣條線的調查數據及搜集水底聲音的資料，研究員估計在香港水域約有55至152隻江豚。春季是江豚出沒的高峰期，而秋季的江豚數目則明顯減少，顯示在這季節很多江豚都會離開香港。從現時的季節性分佈來看，江豚似乎會在不同季節由南面水域遷移至東面水域。但另一個可能性，是在香港南面生活的江豚，會在夏秋兩季時遷移至香港以南的廣東省水域。事實上，在香港鄰近水域的調查亦發現，香港以南之廣東水域在夏季時會有更多江豚出沒。 Using the line-transect survey method along with acoustic data collection, the minimum abundance of finless porpoise in Hong Kong has been estimated to vary from 55 porpoises in autumn to 152 porpoises in spring, indicating a good portion of animals are outside of Hong Kong in autumn months. While porpoises appear to undergo some seasonal shifts from southern waters to eastern waters, this may not tell the whole story, as porpoises may also shift from southern waters to offshore waters in Guangdong Province in summer and autumn months. Indeed, surveys in adjacent Chinese waters also showed that more porpoises occurred south of Hong Kong’s territorial boundary in the summer months.

無法分辨個別江豚的身份令研究工作舉步維艱 The inability to identify individual porpoises makes them a very challenging research subject to understand their occurrence and abundance

香港的江豚數目估計已十年未曾更新，但研究員卻無意著力更新這個數字。為甚麼呢？那是因為更新香港的江豚數目意義不大。經過十多年的江豚研究，研究員明白他們根本無法掌握個別江豚在香港的出現情況及移動模式。由於無法辨認個別江豚，所以無人知曉在香港出現的江豚會否日復日、月復月、年復年地出現。即是說，今天看到的江豚跟明天的江豚是否相同、又或去年看到的江豚是否今年所看到的，研究員都無法得悉。再者，要找出香港所屬的江豚種群的分佈範圍，幾乎是不可能達成的任務，因為此種群範圍的邊界線可能遠離香港數十、甚至數百公里。所以，如果無法知道個別江豚的身份及無法掌握江豚種群的出沒範圍，在香港的某一地方及某一時間所估計出來的數目統計，可能並無太大意義。所以，研究員現時主要把資源花在找出江豚的重要棲身地，以保護這些水域免受人為活動的破壞。 The abundance estimate of finless porpoises in Hong Kong is fairly out-dated because the research was done about ten years ago, but researchers are not keen on updating this estimate. Why? It is mainly because estimating abundance of porpoises may not be a meaningful exercise after all. The main problem is that researchers may never know anything about the residency and individual movement patterns of the finless porpoises they have been studying in Hong Kong for over a decade. And because porpoises cannot be identified individually, no one will ever know whether the same porpoises have been showing up in Hong Kong everyday, every month, or from year to year. Also, it would virtually be a “mission impossible” to determine the range of the population, which may extend tens or even hundreds of kilometers away from Hong Kong waters. So researchers will never have a good handle on how to define the population boundary for Hong Kong’s finless porpoises. Basically, without knowing the identity of individual porpoises, and with virtually no information on their ranging pattern or the boundaries of the population, counting the number of porpoises occurring in a certain area and specified period of time may have limited value. Therefore, the focus of the current research in Hong Kong is more geared towards determining important porpoise habitat areas and to ensure that porpoises can continue to utilize these habitats without degradation.

江豚的行為 Their behaviour

江豚出現時大多在水面快速滾動 During most encounters, porpoises were observed rolling quickly on the water surface

上文提及，江豚的性格十分害羞，行蹤不定，又經常避開船隻，包括研究船也不例外。牠們一般會在水面快速滾動，匆匆吸一口氣後又再潛進水中，不留半點蹤跡。研究員常形容看到江豚在水面的情況，就像看見一個車輪在水中載浮載沉。當海面異常平靜、江豚在水面附近覓食時，間中亦會觀察到牠們在水面追魚時泛起少許水花。奇怪的是，當被迎面而來的船隻嚇倒，或在海況較差的時候，江豚反而會在水面上露出較多身體部分。那是因為在水面平靜時，江豚只要微微將頭頂的氣孔露出水面就可呼吸，但在海況較差時，牠們則需花較大力氣才可升到水面呼吸，研究員亦在此時才可看到牠們約半個身軀。在十五個研究江豚的年頭裡，研究員只曾觀察過一次令人歎為觀止的情景︰一群非常活躍的江豚不停在水面向前躍動，甚至將尾鰭露出水面之上。在過去的日子，研究員亦曾觀察到江豚罕有地在水中側身游動並露出少許尾鰭，或在深潛時將尾鰭露出水面。

As mentioned before, finless porpoises are typically shy and elusive, and they often try to avoid approaching vessels, including research vessels. They typically roll their backs on the water surface, quickly taking a breath and going back down into the water without displaying much other behaviour. That’s why some researchers have described encounters as similar to seeing a tire floating on the water. When the sea is very calm, porpoises have occasionally been observed feeding at the surface and sometimes causing minor water splashes. Interestingly, when porpoises show more of

一大群江豚活躍在水面的罕有情景 A very rare occasion with a large group of active porpoises

their bodies above the surface of the water (i.e. arching their backs), they are usually reacting to an approaching vessel or it is during rougher sea conditions.

In calm sea conditions, they can take a breath effortlessly by just exposing their blowhole above the water surface. But in rougher seas, or when they need to take a quick breath in a hurry, they need to clear the water surface further in order to do so, and that’s when more of their body can be seen. In 15 years of porpoise studies locally, researchers have only encountered one group of very active finless porpoises, which were engaged in vigorous porpoising behaviour, and lifting their tails out of the water. They have rarely been seen swimming sideways to expose their pectoral fin, or lifting their fluke up in the air before making a dive.

研究員在陸上或空中觀察江豚時，都可看到牠們一些有趣的行為。牠們在水面以下通常都十分活躍，並在追魚時不斷轉換方向；由於牠們的頸項較為柔韌，所以有時會扭動頸項以快速轉向。江豚的游泳速度較為迅速，靈活性方面比中華白海豚更勝一籌﹗根據陸地觀察研究，江豚的潛泳時間及在水面以上的時間均十分短暫，分別是平均50秒及90秒左右；而江豚群體一般花六成時間在水面附近活動，潛泳的時間只佔四成。雖然在船上觀察江豚活動是一件十分困難的事情，但由陸上或空中觀察時，牠們卻是有趣的研究對象。

江豚在水面嬉戲及快速游動 Two playful porpoises moving quickly on water surface and making some splashes

江豚花大部時間在水面附近活動 Finless porpoises spend the majority of their time near the water surface

When observed from land or from the air, porpoises actually display more interesting behaviour. They can be quite active at the water surface, and frequently change directions during foraging activities. At times they even “turn” their neck and make sharp turns, which is possible because of their flexible “neck”. They are fast swimmers too, and seem to be more agile than the Chinese white dolphins. A land-based study in the past revealed that their dive and surface times are quite short, with an average of 50 and 90 seconds respectively. The same study also determined that porpoise groups spent about 60% of their time at or near the surface but only 40% of their time on longer dives. So, even though porpoises are difficult animals to observe from a boat, they are very good study subjects for land-based observations and aerial surveys.

江豚大多三五成群出沒 A typical group size of three finless porpoises

在兩種江豚所及之處，群體成員數目一般都是十分少，這跟大多數近岸海豚品種(如中華白海豚)的情況一樣。在香港水域，江豚的平均群體成員數目為3隻，而牠們單獨出現的情況亦非常普遍。事實上，要準確地從船上估計江豚的群體成員數目亦有困難，因為江豚的動作快速敏捷、個體之間的體色相似，而且個別江豚亦難以分辨，尤其當較大的群體分散成數個小組並在不同方向出現。所以研究員往往未能充分掌握江豚的群體成員數量，甚或低估其數目。舉例說，香港有紀錄以來最大的江豚群體是從直升機上觀察到的35 隻，但其實牠們並不是緊密靠在一起，而是分散成數個小組。牠們聚在一起，可能是因為當時有大批食物，吸引了數個可能互不相干的小群體聚在一起覓食。研究員相信，江豚的社群結構很大可能跟中華白海豚一樣鬆散，而且採取機會主義的覓食策略。 Throughout the species range, the group size of finless porpoise tends to be very small, which is typical of coastal cetaceans.

In Hong Kong, the

average group size is about three animals, and it is actually quite common to see animals occurring alone. However, determining their group size can be quite tricky during vessel surveys because they move very quickly so it can be difficult to determine the number of individuals being observed. Also, colouration amongst different individuals is almost identical, and it is impossible to identify individuals, so researchers could easily underestimate group size. Moreover, larger groups of porpoises tend to be dispersed into smaller subgroups which may be moving in different

估計江豚群體數目是十分具挑戰性的工作 Accurately estimating the group size of finless porpoises is quite a challenging task

directions, and that makes group size estimates even more challenging. For example, the largest porpoise group in Hong Kong was observed during a helicopter survey, when a total of 35 porpoises were estimated in the group! But the group size estimate was actually the sum of several subgroups dispersed in the general area, so the porpoises may have just gathered loosely in that area to take advantage of a good feeding opportunity there rather than having some social affinities to one another. It is suspected that finless porpoises are opportunistic feeders just like the Chinese white dolphins, so their social structure may be very fluid as well.

鼠海豚科所運用的聲音溝通系統有一個共通點，就是是採用超高頻率的聲音，江豚亦不例外。香港有關江豚的發聲行為研究發現，江豚發出的超高頻率聲波能高達到142千赫 (註︰人類可聽到的聲音範圍大約在20赫至20千赫)，雖然牠們亦能發出較低頻的卡嗒聲，而當牠們靠近水中咪高峰時，我們也間中可聽到牠們發出的聲音，但人類一般不能聽到江豚發出的大部分聲音。這些超高頻的發聲對江豚探測四周水底環境時非常有用，尤其是牠們所用的頻道遠高於其他海洋生物及水底噪音。江豚獨特的發聲行為，讓研究員可用聲納探測器確定牠們是否存在，但前提是牠們必須正在發聲及在水中咪高峰附近出現。 All members of the porpoise family display distinct acoustic repertoires of ultra-high frequency sound, and the finless porpoises are no exception. Acoustic studies in Hong Kong showed that the local porpoises exhibit very high-frequency ultrasonic pulses, with peak energy reaching 142 kHz (note: the audible range of human is usually around 20 Hz to 20 kHz)! They also emit some broadband clicks, which can be heard when they are very close to a hydrophone, but most sounds they produce are generally inaudible to human ears. Actually, the ultra-high frequency sounds they produce can be quite useful for acoustic detection, as they utilize a frequency channel well beyond the sounds from other marine organisms and underwater noise. Therefore, detecting the presence of finless porpoises using acoustic methods can be quite effective as long as they are producing sounds when they are near the hydrophone.

江豚的一生 Life history 江豚的年齡鑑定工作，主要依靠其牙齒橫切面的年輪分析(就像計算樹木橫切面的年輪)，而江豚的牙齒則是從擱淺屍體取下來的。鯨豚專家以往普遍認為所有鼠海豚壽命較短，大多不會活超過20歲。但香港的江豚研究發現，本地最年長的江豚達33歲，亦可能是鼠海豚科的最老紀錄。其實，在其他地方進行有關鼠海豚的年齡研究，由於樣本主要來自被漁網誤捕的死亡個體，所以這些「英年早逝」的鼠海豚可能未能活到老就已死掉，這可能令研究結果有所偏差。當然，我們亦不能排除香港江豚較其他鼠海豚長壽的可能性。江豚牙齒被染色後的橫切面 Cross-section of a finless porpoise tooth after sectioning and staining process

The estimated age of a finless porpoise is based on analysis of dentinal growth layers from a crosssection of the teeth that are retrieved from stranded specimens; this method is similar to reading the rings for growth layers observed in tree trunks. Porpoises are often thought to have short life spans, rarely reaching the age of 20. But to researchers’ surprise, the oldest finless porpoise aged thus far in Hong Kong was 33 years old, which is probably the oldest found in any porpoise species. It is possible that studies of porpoise life spans in other areas are heavily biased by examining by-caught animals only so these animals would not have been able to reach their known maximum age; or maybe finless porpoises in Hong Kong just enjoy a longer life span than other porpoises.

江豚的成長亦是與眾不同的。剛出生的幼豚一般身長只有約67-70 厘米，成年最長的亦不會超過1.8 米。幼豚出生時體型十分細小及纖瘦，就像一尾中型的魚類；牠們大多在秋末至初冬的月份(即每年的10月至翌年的1月)誕生，江豚亦正於此時開始移至香港南面水域。幼豚在出生後首一年

剛出生的江豚只有少於70厘米的體長，體形纖瘦，身上亦有多條胎褶。 Newborn calves are less than 70cm in length and quite skinny. The foetal folds were clearly visible on this newborn porpoise.

的成長速度非常迅速，一歲過後成長速度才開始放緩。根據一個較小的數據樣本，研究員估計雄性江豚在4-5歲已達性成熟期，而雌性亦可在5-6歲左右開始交配繁殖；由於江豚在較年輕時已達性成熟期，約每隔一年就可生產一胎，所以牠們一生中應能比中華白海豚孕育更多幼豚。 The growth of porpoises is quite interesting too. When they are first born, they are at about 6770 cm in length, and can grow up to about 1.8 m in length. The newborn porpoises are very small and thin, pretty similar to a mediumsized fish. Most births of local porpoises occur between late autumn and early winter months (around October to January), and that is when more porpoises start to move inshore to the

在剛死去不久的江豚頭部可見漂亮的斑紋及淺色的「唇印」 Beautiful body stripes and light patches around lips of the head region can be found on a freshly stranded porpoise

southern waters of Hong Kong. After birth, the growth of newborn porpoises is very rapid, especially in their first year and then begins to level-off thereafter. Based on a small sample size, researchers have determined that male porpoises can reach sexual maturity between

the ages of 4-5 years, while females can reach sexual maturity at the ages of 5-6 years. In contrast to the Chinese white dolphins, finless porpoises are likely capable of producing more offspring given their early age of sexual maturity and shorter calving interval.

與中華白海豚相比，在香港生活的江豚較不會「揀飲擇食」。根據牠們的胃部食物殘渣分析，本地江豚主要獵食25種魚類、 6種頭足類(包括魷魚、墨魚及八爪魚)及一種蝦。這些江豚賴以為生的食物主要是一些近岸底層及中層的品種，所以研究員估計，江豚主要在近岸不同水深的地方覓食。牠們所吃的海產種類雖跟中華白海豚有所重疊(主要是一些河口生活的魚類)，但江豚更會獵食其他近岸的海洋性魚類。這兩個品種不同的分佈及棲身地運用中亦反映了牠們的覓食習慣。 Unlike Chinese white dolphins, finless porpoises in Hong Kong appear to be less selective when it comes to their prey. From

在這條被漁網誤捕致死的江豚胃部，發現一些未被完全消化的魚類，這有助研究員瞭解江豚的覓食習性。 From the stomach content of this by-caught finless porpoise, some undigested fishes were found, which could aid researchers to study its feeding habits.

examining stomach contents of stranded animals, researchers found that local porpoises preyed upon 25 species of fish, six species of cephalopods (i.e. squids, cuttlefishes, and octopuses) and one species of shrimp. These prey species are primarily inshore, bottomdwelling and mid-water species, suggesting that porpoises probably feed in different levels of the water column in nearshore habitats. Even though there is some overlap in targeted prey species with Chinese white dolphins (mainly some estuarine fishes), porpoises also exploit other coastal, non-estuarine habitats. This is also reflected in the contrasting distribution and habitat requirements of these two resident cetaceans!

這些魷魚及蝦均在一條擱淺江豚的胃內找到 These squids and a shrimp were found inside the stomach of a stranded porpoise

江豚面對的威脅 Their existing threats

跟中華白海豚及其他近岸鯨豚品種一般，江豚每天亦要面對人類活動及沿岸發展所帶來的一些危機。每年香港平均都有約10至20條江豚在擱淺，而研究員亦會嘗試找出牠們的死因。雖然中華白海豚和江豚的生活方式十分不同，但牠們在香港水域均面對同樣的威脅，如被漁網誤捕、被船隻撞擊、及由海水污染、沿岸發展及水底噪音帶來的問題。

Similar to other coastal cetacean species such as the Chinese white dolphin, the finless porpoise often experiences conflict with human activities and coastal development. On average, about 10-20 dead porpoises are washed ashore along Hong Kong’s coastlines annually, and researchers have worked very hard to determine their causes of death. Even though dolphins and porpoises have very contrasting lifestyles, they both share similar problems in Hong Kong when it comes to human-related threats, which include incidental entanglement by fishing nets, vessel collisions, habitat degradation due to pollution, coastal development and acoustic disturbance.

一條剛死去的江豚屍體 A fresh carcass of finless porpoise

被漁網誤捕可以說是全球所有鼠海豚要面對的最大威脅，這亦是導致香港江豚死亡的主要原因。在19962004年期間，有24隻江豚被鑑定出死因，其中14隻均是被拖網或流刺網纏繞致死，而且數目可能已比實際

這條江豚被漁網纏繞而窒息致死 This porpoise was entangled and had drowned in a fishing net

情況為低，因為一些江豚屍體可能因太腐爛，令研究員無法在其身上找到被漁網纏繞的痕跡。雖然研究員從未在香港水域發現江豚跟在漁船後覓食，但一些離岸作業的漁民，則指曾經觀察到江豚在漁網旁覓食。另外很多流刺網亦會在香港毗鄰的水域作業，這些作業都會增加江豚被漁網誤捕的機會。值得一提的是，江豚可能因沒有中華白海豚般強壯，所以牠們被漁網纏繞後亦無法掙脫。相反，中華白海豚身上經常有被漁網纏過的傷口或疤痕。所以，相比起中華白海豚，漁網誤捕對江豚來說是一個更嚴重的威脅。 Just like other members of the porpoise family, incidental by-catch of finless porpoises appears to be a significant problem everywhere throughout their range, including Hong Kong’s waters, where it appears to be the primary cause of death for local porpoises. For example, from 1996-2004, the cause of death for 14 of the 24 porpoises was determined to be (or likely to be) incidental capture by trawl nets or gill nets. The percentage may have been even higher, but since most recovered porpoise carcasses were moderately or badly decomposed, evidence of being caught in fishing nets could not be determined when the carcasses were examined. Although finless porpoises have not been observed feeding behind fishing boats in Hong Kong, fishermen report that at times porpoises do feed near fishing boats in offshore waters. There is also probably more gill net fishing activities in waters adjacent to Hong Kong. And because porpoises are not as capable as Chinese white dolphins in breaking free from fishing gear after entanglement, they are more vulnerable.

相比起中華白海豚，江豚對繁忙的高速船隻航行更為敏感。 In comparison to Chinese white dolphins, finless porpoises may be even more sensitive to the busy traffic of high-speed ferries.

相比起中華白海豚，香港江豚一般在較少受到人類活動影響的水域出沒，但江豚某部分的分佈範圍卻跟一些繁忙的航道重疊。譬如說，在南大嶼山水域的航道，每天都有頻繁的船隻來往(尤其是來往港澳兩地的高速船)，而這航道正是在江豚的重要棲息地中間穿過。一些江豚屍體解剖結果亦顯示，被船隻撞擊是導致香港江豚死亡的其中一個主要原因。真實情況可能更糟，因為當被高速船撞擊時，江豚很可能已因「粉身碎骨」而無法檢獲，令研究員及公眾無法知悉這些意外曾發生。所以現時仍很難確定船隻撞擊威脅江豚存活的真實程度。 Even though finless porpoises are found in more undisturbed areas of Hong Kong (compared with Chinese white dolphins), part of their range still overlaps with vessel traffic routes. For example, the South Lantau Vessel Fairway has an extremely high amount of vessel traffic (especially high-speed ferries that travel between Hong Kong and Macau/Zhuhai) that passes through an important habitat of local porpoises. Necropsy examinations show that vessel collision is another significant cause of porpoise mortality. Direct collisions with highspeed vessels would most likely be lethal to porpoises but their carcasses may never be recovered due to the severe impact. Therefore, it is difficult to understand the magnitude of the impact of vessel collisions presently.

當然，大部分江豚未必會在繁忙的航道被船撞擊致死，但頻繁的船隻航行卻為牠們帶來另一個威脅 - 水底噪音。水底噪音的影響不容小覷，可迫使牠們離開一些重要的棲身地。近年，研究員發現江豚已逐漸放棄使用大嶼山南面的近岸水域，例如曾有很多江豚出沒紀錄的貝澳灣。在船隻來往日趨繁忙的情況下，愈來愈少江豚願意「鋌而走險」，由石鼓洲至索罟群島之間的離岸水域，橫越航道而游進貝澳灣的近岸水域。由於江豚對研究船隻及其發出的聲響十分敏感，因此實在有必要進行陸上觀察，研究江豚是否被繁忙的海上交通逼離原本適合的棲息地。 Porpoises that are not harmed physically by vessel collision face acoustic disturbances caused by the high amount of vessel traffic, which presents another significant threat. Researchers have noticed in recent years that porpoises seem to be avoiding the coastline of South Lantau, especially within Pui O Wan, which was once an important habitat for porpoises as evidenced by their frequent occurrence there. It is possible that fewer porpoises will risk entering the area because of the increase in vessel traffic using the fairway, and so now, they appear to forage mainly in the waters between Shek Kwu Chau and the Soko Islands instead of moving inshore to Pui O Wan. Since porpoises are sensitive to boats and boat noise, land-based studies at suitable platforms will be needed to study the possible displacement of porpoises from preferred habitat by the busy vessel traffic.

眾所周知，香港的海水污染問題十分嚴重，不少住宅及工業污水、農地使用的殺蟲劑均在很少、甚至沒有處理的情況下排出大海。海洋環境污染物對江豚 - 生物鏈的最高消費者 - 造成的負面影響更為顯著，因為江豚在食物鏈中所攝取的污染物濃度比其他生物高出很多倍，而且牠們亦無法將這些污染物排出體外，故牠們體內的污染物濃度會隨年齡不斷增加。在擱淺的江豚體內，研究員找到數種高濃度的環境污染物，包括一些重金屬(如水銀、鎘等)和有機化氯物(如滴滴涕、多氯聯苯等)；個別雄性江豚體內的環境污染物濃度更錄得極高的水平。在某些個體，水銀的濃度甚至高至一個可令瓶鼻海豚患肝病的水平。 Water pollution problems in Hong Kong are well documented, as sewage from residential and industrial sectors and insecticides from agricultural farming drain into the sea with little to no treatment. The problem of environmental contaminants is exemplified in the case of finless porpoises because they are top predators in the marine ecosystem. Toxic chemicals can bioaccumulate and biomagnify in their bodies as chemicals make their way up the food chain. Several types of environmental contaminants have been found in the blubber, liver and kidney of stranded porpoises in high concentrations, including heavy metals (such as mercury and cadmium) and organochlorines (such as DDT and PCB). For some individuals, the concentrations of DDT and PCB were extremely high and for males, the concentrations of contaminants increase throughout their lives. Mercury levels in some specimens were very high and in the range of concentrations previously found to be associated with liver disease in bottlenose dolphins.

江豚出沒範圍的海水較為清澈，但當中所含有的環境污染物卻是肉眼所不能看見 Although it appears that the waters within porpoise habitat are fairly pristine, the environmental contaminants that can cause health problems for them are invisible.

環境污染物如何影響香港江豚的健康呢？雖然研究員仍未能完滿解答這個問題，但有證據顯示，高濃度的污染物會對江豚的健康及生殖能力構成負面影響。我們知道高濃度的污染物能令江豚的免疫系統受損，而母豚更會將一些污染物經胎盤及哺乳傳到幼豚體內，這亦可能解釋了為何香港剛出生的江豚夭折率比較高。可以肯定的是，當香港的江豚已要面對生活環境的各種威脅，環境污染物只會令牠們的健康情況「雪上加霜」，甚至影響牠們的存活。 So how do these contaminants affect our poor porpoises? Although the specific health implications of environmental contaminants for porpoises are not fully understood at present, some believe that the high levels of pollutants may pose serious health and reproductive problems. The contaminants can weaken their immune system, and this may be a factor in the high mortality rate of their neonates. Mothers will offload their pollutants onto their newborn infants during gestation and especially through lactation. It is almost certain that along with the other anthropogenic factors stressing porpoises in Hong Kong, environmental contaminants will further compromise their overall health, eventually jeopardizing their survival.

在身體積存高濃度環境污物會令這些江豚的免疫力下降 Bioaccumulation of high concentration of environmental contaminants can weaken the immune system of these finless porpoises

除了上述問題，沿岸發展及填海工程對江豚棲身地帶來的破壞，更長遠影響牠們能否繼續於香港水域生活。在各種沿岸發展模式中，填海工程的影響最大，因江豚的生境將因而永久消失，被填去的海域亦無法恢復原狀，而且牠們覓食的機會也會受到嚴重影響。再者，填海工程牽涉海床挖掘污泥及傾倒污泥，這都會令沉積於海床多年的污染物，再次釋放到水中，並被江豚的食物所吸收，令江豚體內積存更多污染物。

香港江豚的生活將會受到未來的沿岸發展所威脅 The future survival of finless porpoises will be seriously hampered by various coastal development projects

Last but not least, habitat degradation by coastal development and reclamation will affect the survival of porpoises in Hong Kong in the long run. The worst coastal development projects involve reclamation, which results in permanent and irreversible loss of habitat for local porpoises and may greatly compromise their foraging opportunities. Moreover, reclamation will involve seabed dredging and disposal, which are activities that will worsen the problem of water pollution by re-suspending contaminants that have settled into marine sediments, and thus being exposed again to local porpoises through their food.

00 海上的打樁工程會對江豚帶來一些噪音滋擾 Piling activities at sea will cause some acoustic disturbance to the local porpoises

在過去，香港東面及南面的水域，即江豚的生境，一直甚少受到沿岸發展工程的威脅。但是，這情況可能會在未來逆轉，因為已有數個海上工程將會或計劃在江豚的棲身地水域進行。譬如說，香港電燈公司及中華電力公司分別計劃在南丫島西南面的水域及香港東面離岸水域，興建兩個風力發電場。這些建築物的興建將對江豚造成一些負面的影響，包括打樁及挖泥工程，而來往工地和將來風力發電場的船隻亦可能增加。另外，風力發電場在正式運作後，風車葉輪轉動聲音可能會傳到水中，並影響到江豚的聽覺及溝通能力。而風車的基座亦會佔據一些海床，令江豚部份的棲身地受到影響。 In the past, porpoise habitats in southern and eastern waters of Hong Kong have not been the targets for coastal development projects. However, this is likely to change in the near future, with several impending and proposed infrastructure projects within porpoise habitat. For example, two offshore wind farms are scheduled to be built in the southwestern waters of Lamma Island by Hong Kong Electric (HEC) and in the eastern offshore waters by China Light and Power (CLP) to generate renewable energy. During the construction, porpoises will likely be affected by piling and dredging activities, as well as the increased amount of vessel traffic servicing these work sites. And when the wind farms are in operation, it is uncertain whether the noise generated by the wind turbines will be transmitted into the water column and affect porpoises in the area. The wind turbine foundations will also occupy some seafloor area and result in habitat loss.

另一項引起研究員深切關注的沿岸發展項目，就是擬建在石鼓洲的綜合廢物管理設施。石鼓洲西南水域是江豚的一個重要棲息地，而此工程將牽涉的小型填海工程亦正與江豚於此處的重要棲息地重疊，所以此工程必會對江豚構成一定程度的影響。而且，現時仍難以估計在工程進行及營運期間，此水域愈發頻繁的海上交通，會否影響江豚。作為此工程的倡導者，香港政府已承諾在石鼓洲附近設立海岸公園，作為彌補江豚生境流失的補償措施。研究員期望此保育措施，能把這裡人為活動的負面影響減至最低，讓江豚能繼續在該處水域生活。 Another noticeable development within porpoise habitat will be the proposed Integrated Waste Management Facilities at Shek Kwu Chau. The southwestern corner of Shek Kwu Chau has been identified as one of the hotspots important to porpoises in Hong Kong, and this project will involve reclamation right in this important area. Therefore, such habitat loss will certainly affect porpoises using this area in the future. In addition, it is uncertain whether the vessel movement during and after the construction will result in additional acoustic disturbances to the porpoises utilizing the general area. The project proponent, our Hong Kong Government, has committed to establishing a marine park in nearby adjacent waters where porpoises occur regularly, as a compensation measure for the predicted future loss of habitat. Hopefully this strategy will result in an overall reduction of the total impacts of human activities on the porpoises in the long run.

除了人類活動的威脅，值得一提的是，自然界也有一些因素會導致江豚死亡，這包括被鯊魚襲擊及患病。在香港擱淺的江豚屍體中，研究員有時會在其肺部找到一些寄生蟲(又名肺蠕蟲)，情況嚴重時甚至可見寄生蟲阻塞了部分呼吸道﹗ 然而，即使在江豚體內發現肺蠕蟲，亦不能就此斷定這些寄生蟲導致江豚死亡，因為肺蠕蟲也可在健康的江豚體內找到。但感染寄生蟲或其他疾病，可能會降低江豚的免疫力，間接令牠們死亡。 Besides human-induced threats, there are also several mortality causes of finless porpoises that are natural factors, such as shark attack and diseases. In particular, heavy lungworm infections can be commonly found in stranded porpoises in Hong Kong, and in some animals, lungworm infections can be severe enough to cause complete blockage of their respiratory passages! However, it is uncertain whether the lungworm infection is the actual cause of death for these stranded porpoises as some healthy animals have the ability to cope with parasites. It is possible that the infection of parasites and

能否令江豚繼續在香港水域生活將會是保育人員所面對的一個嚴峻挑戰 It will be an uphill battle for conservationists to ensure the continued use of Hong Kong waters by finless porpoises

disease is somehow related to other reasons such as the weakening of their immune system.

江豚的將來 Their Future

雖然江豚在香港受到數條法例保護，但要在香港既繁忙又污染的水域繼續生活，牠們仍要面對不少威脅和挑戰。我們究竟可以做些甚麼，才可保護這些既可愛但又常被港人遺忘的原居民呢？ Although finless porpoises are fully protected by several laws and ordinances in Hong Kong, their long-term survival in the waters of Hong Kong is still hampered by various

我們是否有決心保護這些珍貴的江豚？ Do we have the determination to protect our precious finless porpoises living in our waters?

threats they are facing in our busy and polluted waters. After taking a glance at their interesting lives and the problems we have contributed to their plight, what can we humans do to help this lovely resident species that has been largely ignored in the past?

從政府層面，漁農自然護理署一直資助一項長期監察香港鯨豚的研究項目，以了解江豚的種群生物學和在香港的最新情況。「環境影響評估條例」亦可確保沿岸發展工程對環境造成的影響 (包括對江豚的影響) 得到仔細評估，並把影響儘量減低。在上述的數項與江豚有關的沿岸工程，本地研究員亦為保護江豚把關，希望這些工程不會嚴重影響江豚在香港的生活。但要做到這點，工程倡導者及決策者必須接納及認真執行鯨豚專家的意見。更重要的是，江豚保育有賴香港市民的支持及通力合作。市民可向有關當局表達關注及提出意見，讓江豚免受發展工程威脅。 At the government level, the AFCD has been funding a long-term monitoring research project on the finless porpoise to gather data on different aspects of their population biology, and to understand their status in Hong Kong. The Environmental Impact Assessment (EIA) process is also instrumental to ensure the impacts of coastal development projects on finless porpoises can be properly assessed, minimzed and mitigated. For the few development projects mentioned above, local researchers have worked diligently to assess the potential impacts and devise appropriate mitigation measures. The ultimate goal is that these projects will not adversely affect the overall usage of porpoises in Hong Kong, but it will take the project proponents and decision makers agreeing to implement the suggestions and advice from researchers in order to achieve this goal. The Hong Kong public should also realize that it will take a concerted effort from local communities to voice their concerns, opinions and desire to save the porpoises from further harm of development activities.

保護江豚有賴研究員、政府部門、保育團體、決策者及市民多方面的通力合作 Conservation of finless porpoises relies on the collaboration between researchers, conservation groups, government officials, decision makers, and most importantly the Hong Kong public

香港雖然有一個完善的海岸公園制度，並已設立了四個海岸公園及一個海岸保護區，但這些保護區均未能覆蓋江豚的出沒範圍。事實上，有數個擬建的海岸公園都與江豚一些重要棲身地重疊，包括西南大嶼山的分流海岸公園、南大嶼山的索罟群島海岸公園、及南丫島南面的海岸公園，但這些建議直至現在仍是「只聞樓梯響」，甚至是提出了超過十年還未能落實。為江豚設立海岸公園可使牠們免受高速船撞擊、破壞性捕魚活動及海上工程的影響。為確保江豚能繼續於香港生活，設立這些海岸公園實在刻不容緩。 Although Hong Kong has a marine park system in place, with four marine parks and one marine reserve being established so far, none of these protected areas cover the range of finless porpoises in Hong Kong.

為江豚設立保護區實在急不容緩 Urgent actions need to be taken to establish marine protected areas for the protection of finless porpoises

Several marine parks have been proposed to overlap with important porpoise habitat, such as the Fan Lau Marine Park in Southwest Lantau, the Soko Islands Marine Park in South Lantau and the South Lamma Marine Park, but it is uncertain when these proposed marine parks will be established. In order to promote the continued existence of porpoises in Hong Kong waters, the establishment of these marine parks should proceed as soon as possible to safeguard important porpoise habitat from vessel traffic, destructive fishing activities, and marine construction projects.

除了上述的保育措施，在研究江豚的領域上還有多方面需多下功夫，以提供重要資料來協助制定長遠的保育政策。譬如說，針對本地江豚的種群範圍及數目、以及有關個別江豚移動模式的研究，可說是無從入手。而本地江豚被漁網誤捕的情況亦未曾深入研究；研究員必須在漁船上進行觀察，才可得到江豚在香港及鄰近水域被誤捕的準確數字。另一重要領域，就是必須更深入研究環境污染物對江豚種群的健康影響，及研究愈趨繁忙的高速船如何影響牠們。最終，政府需要為江豚訂立一套完整的管理計劃 (就如漁護署於2000年訂立的「香港中華白海豚護理計劃」)，以制定全面的江豚保育政策及特定的研究目標，以確保江豚能世世代代繼續於香港生活。 Besides the abovementioned conservation strategies, there are also many research needs that should be addressed in order to aid conservation efforts for the long-term survival of the local porpoise population. For example, the population range and overall abundance of finless porpoises in Hong Kong and adjacent waters is poorly known at this point, and studying the movement of individual finless porpoises can be very challenging due to many logistical difficulties. The extent of fishery by-catch is still unknown, and a fisheries observer program may be needed to obtain reliable data on porpoise by-catch rates in Hong Kong and adjacent waters. It is also critical to further study the impacts of environmental contaminants on the health status of the porpoise population, or the impacts of acoustic disturbance of high-speed vessel traffic within important porpoise habitat. Ultimately, a management plan with comprehensive conservation strategies and specific research goals, similar to the “Conservation Programme of Chinese white dolphins in Hong Kong” developed by AFCD, will be needed to conserve the local porpoises in the long run.

江豚的保育工作正急需一套完整的管理計劃 More coordinated conservation effort of finless porpoises will require a comprehensive conservation programme initiated by the government

最後，我們深信江豚及海洋的保育工作，除了需要研究員及有關當局通力合作外，更有賴香港市民的認同及身體力行的參與。為減少環境污染物的影響，我們可進食更多有機蔬菜，及減少購買電子產品，因為海洋污染物主要是來自農地的農藥，及電子產品生產過程中所生產的化學物質。我們亦可盡量避免乘搭高速船，以減少這些船隻來往江豚的棲身地。另外，我們可積極參與環評過程中的公眾諮詢，就可能影響江豚生境的發展項目提出關注及建議。我們亦可聯絡地區議員及立法會議員，表達我們保護香港海洋環境的訴求。我們更可將所學到有關本地鯨豚的資訊與朋友分享，讓更多人明白保護海洋環境的重要。

每一個香港市民都可在日常生活中作出一些改變，為江豚及海洋環境保育工作出一分力﹗ To protect finless porpoises and our marine environment in the long run, everyone can make a difference in their daily lives!

We also believe that it is up to every Hong Kong citizens to take this matter into their own hands in order to protect our local finless porpoises and the other marine creatures that live in our territorial waters. To combat the problem of environmental contaminants, we can eat more organic vegetables and purchase less electronic equipment, as the contaminants are drained from agriculture farms and during the manufacturing of electronic equipment. We can reduce our use of high-speed ferries to lessen the impact of vessel traffic. We can become more actively involved in public consultation during the EIA process by voicing our concerns for the porpoises when coastal development projects are threatening porpoise habitat. We can also write to our legislators to demand better protection of our fragile marine environment. Finally, we should also educate others about what we have learnt here so that more people in Hong Kong will know the plight of the dolphins and porpoises living in our waters.

若我們

齊心保護家，相信各人的力量小小也能集腋成裘的鯨豚，為香帶來更港美好的將來﹗ If we a ll c 江豚的

ontribu marine te to im conse prove r our v a t ion eff individ orts, s ual eff mall orts co mbine make d can a huge d if f erence for the dolphin s and porpois es!

江豚的微笑 The Smile of the Finless Porpoise 作者 Author

洪家耀 Samuel Hung

編輯 Editors

John Y. Wang & Thomas A. Jefferson

攝影 Photography 校對 Proofread 設計及插圖 Layout Design and Illustration

特別鳴謝 Special Acknowledgements

聯合出版 Jointly Published By

Samuel Hung, HK Cetacean Research Project Team, John Y. Wang and Thomas A. Jefferson Sammi Ng & Theresa Webb 葉朝霞 Yip Chiu Ha

漁農自然護理署、香港政府飛行服務隊

香港海豚保育學會 Hong Kong Dolphin Conservation Society 香港將軍澳郵政信箱 65457號電話︰2866-2652 電郵︰info@hkdcs.org 傳真︰2357-1373 網址︰www.hkdcs.org 香港自然探索學會 Society of Hong Kong Nature Explorers 九龍觀塘偉業街139-141號兆發工業大廈804室電話︰2866-2652 電郵︰info@shkne.org.hk 傳真︰2357-1373

印刷 Printing 版次 Edition 定價 Price ISBN

網址︰www.shkne.org.hk

保諾時網上印刷有限公司 2011年7月第一版 HK$28 978-988-15467-1-5

在芸芸八十多種鯨豚動物中，生活在香港水域的江豚是其中最鮮為人知的品種，大部份香港人甚至未曾聽過此原居民的名字。但是這種海洋哺乳類動物與動物明星中華白海豚一樣，在我們的海洋環境中有著舉足輕重的角色。本出版物可能是全世界第一本介紹江豚的專書。透過研究員在過去十多年從船上及高空拍攝的數十張珍貴相片，本書將揭開牠們神秘的面紗，讓讀者認識這種海洋精靈精彩的一生，和牠們在香港面對的困境，希望能喚起更多人保護海洋環境的心﹗ Among the 80 or so species of cetaceans (including all whales, dolphins and porpoises), our local finless porpoise is amongst the least known species and has been rarely studied in the wild. Even most people in Hong Kong have not heard of the name of this resident species. However, this marine mammal shares a similarly important role in our marine environment as our famous Chinese white dolphins. This rare publication on the finless porpoise is perhaps the first book ever published on this poorly known species. Through dozens of breathtaking photographs taken from research vessels and from the air by researchers in over a decade, this book will give you a peek at these mysterious creatures, and will introduce their intriguing lives in Hong Kong waters. This book will also tell you about the dilemmas they are facing living in Hong Kong’s waters and that we are all partly responsible for their plight. It is time for us to protect them and their (and our) fragile ISBN 978-988-15467-1-5

港幣HK$28.00

marine environment now!

江豚的微笑 (作者︰洪家耀) The Smile of the Finless Porpoise (Author: Samuel Hung)

Articles inside

江豚的一生

江豚在香港的情況

江豚在香港的歷史