Croatia is well on its way to restrict fishing in 30% of fishing area in the Adriatic

Restricting fisheries in the Jabuka Pit has had multiple positive impacts

Stocks in the Adriatic are in better shape today than they were a decade or two ago and scientists are hopeful that the situation will continue to improve.

Over the last five years (201620) the Croatian fishing fleet has remained largely stable in terms of the total number of vessels both large and small, according to the Croatian Bureau of Statistics. The number of largescale vessels declined by nearly half to 323 units in 2017 and stayed around that level for the next four years. The small-scale fleet increased slightly in 2017 to 7,236 vessels, a number that remained more or less unchanged to 2020. About a fifth of the fleet consists of vessels with very limited activity.

Pelagic species dominate catch volumes

Catches of small pelagic fish (sardines, anchovies, chub, jack, and horse mackerel) account for 90 of the total Croatian catch, demersal species for about 6 and crustaceans and molluscs for about 3. In terms of individual species sardines contribute with the greatest weight, alone accounting for 70 of the total, followed by anchovies. Among the demersal species, catches of hake have dominated in the years 2020 and 2019. Since 2017 fishers targeting demersal species have had to deal with the creation of a fisheries restricted area (FRA) in and around the Jabuka Pit, a region in the Adriatic between Croatia and Italy that is breeding ground and nursery for demersal species, in particular hake and Norway lobster. The FRA is divided

The Jabuka Pit, where a sheries restricted area was created in 2017, has shown a signi cant improvement in the biomass of demersal species in the area with over ow effects bene ting the surrounding parts as well. The FRA is subdivided into three zones, each with different shing restrictions.

into three zones; in the core Zone A any recreational and professional fishing activity with bottom-set nets, bottom trawls, set longlines and traps is prohibited. In Zone B fishing with bottom-set nets, bottom trawls, set longlines and traps is prohibited from 1 September to 31 October each year and allowed (for a maximum of one-two fishing days per week depending on the gear used) the rest of the year, provided that the vessel and/or its master is in possession of a specific authorization and that historical fishing activities in the zone can be demonstrated. In Zone C fishing with bottom-set nets, bottom trawls, set longlines and traps as well as recreational fisheries are prohibited from 1 September to 31 October each year and allowed the rest of the year if the vessel and/or its master is in possession of a specific authorization and if historical fishing activities in the zone can be demonstrated. In zone C, bottom trawls are entitled to fish only on specific days and hours and only two days a week.

Restricting fishing in the Jabuka Pit was an international undertaking

Dr Igor Isajlovi , a scientist at the Institute of Oceanography and Fisheries in Split, is an expert on demersal fisheries who has been measuring the effect of the restrictions of fisheries in the Jabuka Pit. Only a small number of vessels are allowed to operate in that area, he says, as they need to get a special authorisation. The pit is a breeding

ground for most of the demersal species including the two important species for Croatian fishers, hake and Norway lobster. It is one of the main spawning and nursery areas in the Adriatic he says. Declaring the area an FRA was a protracted affair that took years of negotiation and only succeeded in 2017. In fact, twice before in 2015 and 2016 Croatia had tried to close the area bilaterally with Italy, but these efforts only lasted a year. in the end, it was the work of NGOs, scientists from universities and institutions around the world, the GFCM, and the EU that enabled the creation of the FRA. Ultimately, says Dr Isajlovi , the plan is to have 30 of the fishing area in the Adriatic under some kind of restrictive management. Croatia has almost reached that already. Dr Isajlovi points out that the channel areas between the islands are completely closed to bottom trawling for six months in the year, and are only accessible to vessels with small engines of up to 184 kW and for only on two days in the week. The Velebit channel, a strip of water separating the mainland from the islands of Pag, Rab, and Goli Otok, is also completely closed to bottom trawling. Several restrictions are thus already in place. Furthermore, the Croatian coast is more than 5,000 km long and according to EU regulations bottom trawling is forbidden in areas within 1.5 nautical miles of the coast (and within 3 nautical miles where the depth is less than 50 m). This significantly enlarges the restricted area in the Croatian part of the Adriatic.

Adriatic fisheries show positive developments

While fish stocks in the Mediterranean are almost all overfished, Dr Isajlovi considers that over the last few years several positive developments have been seen in the Adriatic including a reduction in fishing effort, an increase in spawning stock biomass, and a reduction in fishing mortality, and he is confident that the situation will continue to improve in the future. Although recruitment shows a negative trend, he attributes that to climate change. Stocks are still overfished, but they are in much better condition then they were 10-15 years ago, he declares. The restrictions in the Jabuka Pit also have an impact on pelagic stocks especially in the central part of the Adriatic. The biomass of demersal species has increased significantly in the FRA and because of the overflow effect the improvements can be noted in demersal fisheries in the surrounding areas. The status of rays and sharks too is improving suggesting that the entire ecosystem has benefited from the restrictions.

Climate change complicates the recovery of fish stocks in the Adriatic as effects such as higher water temperatures or increased acidity interact with human-caused impacts like pollution. This can lead to increased frequency and lethality of phenomena such as eutrophication. In addition, scientists at the Institute of Oceanography and Fisheries have noted the increase in invasive species from the Red Sea and even the Indian Ocean. These are not just fish but also crustaceans and parasites. Climate changes also has an impact on the physiology and biology of native species. The spawning season of bogue (Boops boops), for example, a semi pelagic white fish of the Sparid family, has become about two months longer. Pero Ugarkovi , also from the institute, points to the migration of species such as amberjack and grouper from the southern to the northern Adriatic as an indicator of warming waters. Growth in the biomass of blue fish (Pomatomus saltatrix), a predatory species, to the point where it has become one of the biggest predators in the Adriatic, is another consequence that may be attributable to climate change.

Mario Bartulin, a small-scale sher who focuses on valuable species and high quality, selling his catch at the sh market in Trogir.

Climate change also has some advantages

However, some impacts of climate change are benevolent. Deepwater rose shrimp, one of the most valuable species in the Mediterranean, was mainly caught in the southern Adriatic, but can now increasingly be found in the central Adriatic where it is becoming one of the most important species in the demersal fishery. Over the past several years this crustacean has become the second or third species by weight in demersal catches in the central Adriatic. Moreover, the increase in primary production due to warming waters is favourable for the growth of mussels, and for the cultivation of species such as seabream. The prolongation of the warm season when the fish feed the most has meant that the production cycle can be abbreviated from 24 months to 17-18 months with the support of a selection process in the hatchery. Since climate change is an inescapable fact, we have to adapt by changing our fisheries and aquaculture strategies and by reducing human-induced stressors to make stocks more resilient, says Dr Isajlovi .

Both fisheries and aquaculture should also reduce their own contributions to changing climate by reducing their emissions and adopting approaches that make the economy of these activities more circular. Recycling nets and other fishing gear, for example, greater use of renewables, upgrading vessels to use less energy are some of the measures that will reduce the sector’s carbon footprint. In the aquaculture sector, Dr Leon Grubiši , the head of the oceanography institute’s laboratory for aquaculture, has been working on the AdriAquaNet project (EU Interreg Italy-Croatia) to explore the efficiency of feed formulations that will be more sustainable than currently used products. As a member of a team of researchers he studied the impact on seabass growth performance and gut health of diluting conventional protein sources (fishmeal and vegetable protein) with poultry by-product meal and insect meal. Among other conclusions, the results demonstrated that plant-based diets supplemented with meal from black soldier fly larvae either alone or in combination with poultry by-product meal have great potential as an alternative

feed for seabass. Not only would it be more sustainable, but it also preserves the growth performance and health of the fish, while maintaining the nutritional value of the fillet for human consumption1

Sustainability of fish feeds can be optimised without compromising performance

In their paper to be published in the Journal of Animal Science and Biotechnology, the authors also refer to studies that show the successful replacement of plant ingredients with poultry by-product meal and meal from black soldier fly in fishmeal-free seabream diets. Other work has demonstrated that replacing 15 protein of plant origin with insect or yeast proteins yields significantly higher growth performance and feed intake among juvenile seabass. The use of processed animal proteins, meal based on trimmings from the fish processing industry, and insect meals to replace fishmeal to the extent possible support sustainability and the principles of the circular economy. Fishmeal and fish oil are produced from capture fisheries of small pelagic species and have long been the principle ingredients in fish feeds. However, the sustainability of these fisheries has been called into question as aquaculture production has grown over the years. Demand for fishmeal and oil has pushed up the price of these products adding to fish farmers’ production costs. As a result of these developments, the last couple of decades has seen mounting interest in alternatives that offer similar performance and gut health as well as less environmental impact, without increasing costs.

From left, Pero Ugarković, Dr Igor Isajlović, and Dr Leon Grubišić, scientists at the Institute of Oceanography and Fisheries in Split.

Croatian vessels by type (number)

2016 2017 2018 2019 2020

TOTAL VESSELS (1 + 2) 1. Ships 2. Boats 7,746

628 7,118

Croatian Bureau of Statistics 7,559

323 7,236 7,573

307 7,266 7,614

336 7,278 7,555

325 7,230

Croatian catches and production in tonnes (selected species)

2020 2019 2018

1 TOTAL (2+21+25+31) 2 Fish (3+10) 3 Pelagic fish (4+5+6+7+8+9) 4 Pilchard 5 Anchovy 6 Bluefin tuna 70,973 68,940 65,057

50,134 9,781 900 63,883 61,824 58,010

45,134 7,995 822 69,831 67,513 63,814

46,267 13,251 679

7 Atlantic chub mackerel 8 Jack and horse mackerel 9 Other species 10 Other fish 21 Crustaceans 25 Shellfish 1,966 1,755 521 3,883 925 176 2,116 1,585 358 3,814 1,017 254 1,807 1,464 346 3,699 1,179 393

31 Molluscs Croatian Bureau of Statistics 932 788 746