Aspects of fish ecology in the Alde & Ore estuary

Aspects of Fish Ecology in the Alde & Ore Estuary Complex - 2016

Smelt Osmerus eperlanus

Watercolours by Colin Newman

Synopsis 1.

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Background to estuarine fish surveys Environment Agency WFD Alde & Ore fish survey data Marine conservation zone Hazelwood marshes fish sampling 2016

The need for partnership. Only 25% of estuaries are sampled and almost no saltmarshes are sampled at all.

Most photos by Andrew Excell, Suffolk WT

Kick sampling

6 yr cycle, Reference Conditions & Programmes of Measures Only 25% of estuaries are sampled and no saltmarshes

Colclough et al, 2002 Coates et al, 2007

Fish Survey Sites in the Alde & Ore Estuary Complex

Hazelwood Marshes

Environment Agency WFD TraC Survey Sites 2003-2006 & 2013-2015

Iken Cliffs Aldeburgh

IFM & Suffolk WT Survey 2016

RSPB Reserve

Shingle Street Upper

Boyton Dock

Functional guilds of fish species in estuaries •

Estuarine residents (ER) – Fishes that spend their entire life in estuaries

•

Marine seasonal species (MS) – Fishes that use estuaries for part of the year

•

Freshwater species (FW) – Fishes that are present mainly or exclusively at low salinity values

•

Marine juvenile species (MJ) – Fishes that use estuaries as nursery grounds or during juvenile phases of their life cycle

•

Diadromous species (CA) - species that migrate between fresh and saltwater during different life stages

•

Marine adventitious species (MA) – species that are considered fully marine but inhabit estuaries temporarily

After Elliott and Dewailly, 1995; Hemingway and Elliott, 2002

Fish species captured in Environment Agency surveys 2003-6 & 2013-15 Euryhaline

Middle &

Lower Estuary

Fully marine

Bass

Black Goby

Pogge

Ballan Wrasse

Common Goby

Bull Rout

5 Bearded Rockling

Bib

Eel

Cod

Snake Pipefish

Butterfish

Flounder

Dab

Sole

Common Dragonet

Sand goby

Greater Pipefish

Sprat

Common Sea Snail

Sand smelt

Herring

Thick lipped grey mullet

Lesser Weever

Smelt

Lesser Pipefish

Thin Lipped Grey Mullet

Pollack

3 Spined stickleback

Long Spined Sea Scorion

Transparent Goby

Twaite Shad

Plaice

Viviparous Blenny

34 species and 5757 individual fish captured in total

Marine Conservation Zones

www.balancedseas.org.uk

Illustrative length frequency distributions from the 2010 report Bass Autumn 2005 Boyton Dock

RSPB Reserve

Illustrative length frequency distributions from the 2010 report Iken Cliffs Herring Autumn 2003

Sprat Autumn 2005

Illustrative length frequency distributions from the 2010 report Iken Cliffs Smelt Autumn 2003

Plus 2 fish in the autumn of 2003 at Iken Cliffs and 1 fish at Shingle Street in the autumn of 2005

Illustrative catches from the 2013-2015 data series Bass Site

Period

Number

Size range (mm)

Iken Cliffs

Spring 2014

5

54-76

Iken Cliffs

Autumn 2014

102

56-104

Iken Cliffs

Spring 2015

2

78-90

Iken Cliffs

Autumn 2015

100

30-72

Smelt Site

Period

Number

Size range (mm)

Iken Cliffs

Spring 2014

13

82-112

Iken Cliffs

Autumn 2014

97

70-124

Iken Cliffs

Spring 2015

8

53-125

Iken Cliffs

Autumn 2015

49

64-116

Herring Site

Period

Number

Size range (mm)

Iken Cliffs

Spring 2014

44

104-185

Iken Cliffs

Autumn 2014

100

50-87

Iken Cliffs

Spring 2015

38

55-194

Iken Cliffs

Autumn 2015

23

70-105

RSPB Reserve

Spring 2013

104

48-119

RSPB Reserve

Autumn 2013

76

53-78

RSPB Reserve

Spring 2014

2

86,114

RSPB Reserve

Autumn 2014

101

50-85

RSPB Reserve

Spring 2015

101

40-61

RSPB Reserve

Autumn 2015

25

45-80

Herring (continued) Site

Period

Number

Size range (mm)

Shingle Street

Spring 2013

86

33-73

Shingle Street

Spring 2014

100

39-63

Shingle Street

Autumn 2014

52

43-72

Shingle Street

Spring 2015

3

53-136

Boyton Dock

Spring 2013

109

45-67

Boyton Dock

Autumn 2013

34

49-70

Boyton Dock

Spring 2014

96

46-67

Boyton Dock

Autumn 2014

7

63-75

Boyton Dock

Spring 2015

102

42-57

Boyton Dock

Autumn 2015

23

56-80

Some brief preliminary conclusions about the fish communities in the Alde & Ore system 1. The 2013-15 data set is entirely consistent with the earlier 2003-2006 data set.

2. The community of fishes in the estuary is typical of those East coast estuaries with limited freshwater inputs, significant saline penetration and sluice structure truncation of normal estuarine processes.

3. The estuary acts as significant nursery for herring, with juveniles present in both spring and autumn at all sites. At least two year classes are present. Sprat display a similar distribution, but at lower densities and the species does not seem to penetrate to Iken Cliffs.

4. The estuary acts a significant nursery for bass, with most fish present at Iken Cliffs. At least two year classes are present. Numbers appear to be greater in the autumn months.

5. The 2013 – 2015 data set shows a significant nursery ground for smelt at Iken Cliffs.

Numbers are greater in the autumn. There is evidence of local recruitment, with at least three year classes present. Together with the earlier data set from 2003-2006 and the findings of the 2013 national smelt status review, there is now ample evidence of a selfsupporting smelt population in the system.

Evidence of spawning at Langham Bridge in the freshwater reaches in 2003.

Colclough and Coates, 2013

Smelt in the river Burn , North Norfolk

Eastern IFCA NN RT

Colclough et al, 2005

Lessons Learnt

Habitat Issues

Hazelwood Marshes July & September 2016

60 plus planned breaches (managed realignments) have been constructed in the UK since the early 1990’s. Only 9 have been sampled for fish so far. Natural breaches are rare, so far, and none have been sampled for fish.

Hazelwood Marshes Fish sampling methods

Hazelwood Marshes Fish processing

Summary results of fish sampling at Hazelwood Marshes in July & September 2016 Total Number captured Species

Bass Common Goby Sand Goby Eel Thin lipped grey mullet Sand smelt Flounder Pipefish 3 spined stickleback

TOTAL ALL SPECIES

After Thompson S., 2016

Dicentrarchus labrax Pomatoschistus microps Pomatoschistus minutus Anguilla anguilla Liza ramada Atherina presbyter Platichthys flesus Syngnathus spp Gasterosteus aculeatus

Jul-16 71 2361 6 14 59 87 209 3 745

Sep-16 73 3943 0 0 431 103 6 0 82

3555

4638

Hazelwood Marshes Length frequency distributions for the most common species captured

After Thompson S., 2016

Hazelwood Marshes Length frequency distributions for the most common species captured

Hazelwood Marshes Some of the fish species captured

Flounder & 3 Spined Stickleback

Eel

Common Goby

Hazelwood Marshes Some of the fish species captured

Thin Lipped Grey Mullet

Bass

Pipefish

Bass & Thin Lipped Grey Mullet

Hazelwood Marshes Sampling Locations July 2016

The future?

Ecosystem services evaluation

Thank you!