Migratory fish in the context of wildlife restoration regulations

Concluding the spring series introducing migratory fish in Poland, it is worth mentioning how this issue looks in theNature Restoration Law (NRL). According to Article 5 of the regulation, all European Community member states will proceed with the restoration of marine habitats, restoring their biodiversity and the ecosystem services they provide. The law mandates that habitats for species already protected under the Birds Directive and Annexes II, IV and V of the Habitats Directive be restored first. Annex III of the NRL introduces a list of migratory fish whose habitats and populations are to be given special protection [10].

Elasmobranch fish in the NRL

The list of oceanic and bi-environmental fishes in Appendix III of the NRL includes 22 items (list at the end of the text). It is definitely dominated by elasmobranch fish: sawfish, sharks and rays, among which you will find both relentless wanderers and sedentary species. All of them are threatened with extinction. These items cannot always be identified with specific species, as item 18, for example, covers the entire Rhinobatidae family of about 40 species.

Point 4, on the other hand, are two huge sharks that have little in common (other than subcluster and size): the completely harmless to humans, plankton-eating longnose shark Cetorhinus maximus, and the hated cannibal, white shark Carcharodon carcharias. Items 6 to 15 inclusive can be merged into a single item as the genus Mobula in broad terms, which also includes the manta rays (sea devils) Mobula birostris [3, 8, 9, 11].

Diving and oceanarium enthusiasts may be surprised by the presence in Appendix III of a number of species endemic to certain Indo-Pacific basins, such as Mobula eregoodootenkee. However, let’s remember that an integral part of the European Community are not only the waters of the Mediterranean Sea, the Northeast Atlantic, most of the Baltic Sea and parts of the Black Sea, but also the waters adjacent to the overseas territories of the member states, such as the waters of French Guiana in the South Atlantic, Mayotte and Reunion in the Indian Ocean, New Caledonia in the Pacific or the French Southern and Antarctic Territories in the Antarctic Ocean [7, 12].

The prevalence of elasmobranchs in Annex III is due to several reasons. Back in the late 19th and early 20th centuries. Many were harvested deliberately, such as the Squatina squatina raspberry for leather on the hilt of white weapons, and large sharks for tranny. Some sawfish and roches are still exterminated today as fishing pests that damage nets and gouge out the catch. Basking sharks continue to be caught near swimming areas. However, a much more significant reason for the disappearance of the cartilaginous has become bycatch. Since the 1970s. In the 1970s. To this day, the use of trapping in traditional Chinese medicine is also becoming an increasingly important reason for trapping.

The rapid extinction of rays, sawfish and sharks is facilitated by their way of life. These are not infrequently extreme K-strata, or late-breeding species, producing a pair (sometimes only one or two) of young, once every few years. Although we associate fish with millions of eggs produced by a single female, various forms of oviparity and even true viviparity with a kind of placenta prevail in elasmobranchs. Also, oviparous species produce relatively few eggs compared to bony fish. It is not a matter of coincidence that fin whales, sea turtles and albatrosses, pursuing the same reproductive strategy as chondrichthyans, are disappearing just as fast [1, 2, 3, 5].

With the restoration of populations of certain species comes the hope of revilding (sub)marine environments, and thus slowing the undesirable effects of climate change. Potential climate savers include both apex predators (hence the white shark and roach) and the most efficient plankton filterers (hence the longspine and manta ray) [2].

Bi-environmental fish in NRL

In addition to oceanic chondrichthyans, Annex III lists three species of biennial salmonids (according to other accounts, two salmonids and one coregonid): łososia szlachetnego Salmo salar, troć wędrowną/jeziorną/pstrąga potokowego Salmo trutta oraz sieję ostropyską Coregonus oxyrhynchus. The first two are found in the Polish Baltic Sea. The third’s geographic distribution, status and abundance are controversial among ichthyologists, anglers and environmentalists.

According to the Polish Wikipedia, the sharp-tailed whitefish is irretrievably extinct. Unless it joins the mammoth, gastropod and dodo on the list of species to be resurrected through genetic engineering and assisted reproduction by companies advertising such services. The situation is all the more unfortunate because some 20 years ago optimistic articles were published about the return of this corregonid to the rivers of Europe, the Danish Straits and the North Sea.

However, there is no shortage of voices saying that the sharp-tailed whitefish was not a separate species at all. She was just one of a multitude of small, taxonomically insignificant whitefish falling within the range of variation of the dabbler (common whitefish) Coregonus lavaretus. Taking the latter hypothesis as true, the Rhine and Danish rivers can be stocked with the geographically closest whitefish without resistance. After all, our legendary Wigry whitefish is no longer the fish brought by the Devil himself, but a descendant of the Pejpus (Chudski) whitefish with which the Wigry was stocked in the 19th and 20th centuries. [4, 6, 9].

The Lodge of the Overlooked

Surprisingly absent from the list is the only fully catadromous fish of Eurasia: the European eel Anguilla anguilla. If such common sharks as the slender spiny dogfish Etmopterus pusillus were entered from the category of least concern – LC, why were the much rarer Centrophorus lusitanicus (found in Portuguese waters; threat category EN) or Isogomphodon oxyrhynchus (was in French Guiana, threat category CE) omitted? The basking shark Rhincodon typus was entered, and the whale shark Rhincodon typus was ignored? The white shark is being rescued, then maybe the cephalopod Sphyrna zygaena is worth it too? And certainly the sand tava Carcharias taurus as extinct in the Mediterranean [3, 14].

Protection of migratory fish in Poland

Many migratory Appendix III fish were already protected under various international agreements:

• Bonn Convention on the Protection of Migratory Animals;
• Manila Memorandum on the Conservation of Migratory Sharks;
• Barcelona Convention on Pollution of the Mediterranean Sea;
• Convention for the Protection of the Marine Environment of the Northeast Atlantic Area (OSPAR);
• Berne Convention on the Conservation of Species of European Wildlife and their Habitats;
• Washington Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES);
• Habitats Directive.

In Poland, a number of measures have been taken for decades to lead to the rescue of Atlantic salmon and native sea trout/ trout. The multi-million dollar LIFE projects recently concluded: Active Protection of Trichinella Habitats and Enhancement of the Ecological Corridor of the Drawa River Catchment in Poland (LIFE Drawa Pl) and Construction of a Blue Ecological Corridor along the Valley of the Rega River and its Tributaries (LIFE+Rega) . The whole country is keeping its fingers crossed for the launch of the new program LIFE Drawa Bis .

The Inland Fisheries Institute-State Research Institute has a Department of Migratory Fish, focusing on bi-environmental species: sea trout, salmon and eel from Poland and the southern Baltic Sea. They also receive a lot of attention from the Marine Fisheries Institute-State Research Institute in Gdynia. Therefore, Poland can be considered to be implementing the provisions of the Wildlife Restoration Law for its migratory fish. Unfortunately, much work remains to be done, such as a full count of cross baffles on rivers or assessing the impact of wind farms on fish behavior [10].

List of endangered fish, including migratory fish, from Appendix III of the Wildlife Restoration Law:

1. Dwarf sawfish(Pristis clavata) – rather sedentary, prefers brackish waters;
2. Fine-toothed sawfish(Pristis pectinata) – no data, there were specimens that migrated irregularly (wagranci) far beyond the typical range;
3. Common sawfish(Pristis pristis) – rather sedentary;
4. Longnose shark(Cetorhinus maximus) and white shark(Carcharodon carcharias) – oceanodromous
5. Slender thornback(Etmopterus pusillus) – few data on daily and annual migrations;
6. Mobula alfredi – rather sedentary, possible short wanderings behind zooplankton;
7. Manta ray(Mobula birostris) – oceanodromous;
8. Mediterranean mobula(Mobula mobular) – oceanodromous, migrates around the Mediterranean Sea in the rhythm of the seasons;
9. Mobula rochebrunei – no data available;
10. Mobula japonica – probably oceanodromous;
11. Mobula thurstoni – probably oceanodromous;
12. Mobula eregoodootenkee – little data, reproduction in the shallows;
13. Mobula tarapacana – probably oceanodromous;
14. Mobula kuhlii – little data;
15. Mobula hypostoma – little data;
16. Black-bellied skate(Dipturus nidarosiensis) – geographical distribution is controversial, probably quite sedentary;
17. Grey raja(Rostroraja alba) – sedentary;
18. Rhinobatidae– some sedentary, the family often undergoes taxonomic changes, including species transfers to other families;
19. Sea angel(Squatina squatina) – northern oceanodromic populations migrate regularly in the rhythm of the seasons, southern populations rather sedentary, may undertake irregular migrations from the shelf to estuaries;
20. Atlanticsalmon (Salmo salar) – bi-environmental;
21. Seatrout (Salmo trutta) – bi-environmental;
22. Sharp-tailed whitefish(Coregonus oxyrhynchus) – bi-environmental.

Zdj. główne: Krzysztof Gruszecki

In the article, I used, among other things. From the works:

1. Coelho R., Erzini K. (2008). Effects of fishing methods on deep water shark species caught as by-catch off southern Portugal. Hydrobiology 606(1): 187-193.
2. Dulvy N.K., Davidson L.N., Kyne P.M., Simpfendorfer C.A., Harrison L.R., Carlson J.K. & Fordham S.V. (2016). Ghosts of the coast: global extinction risk and conservation of sawfishes. Aquatic Conservation: Marine and Freshwater Ecosystems, 26(1), 134-153.
3. Fowler S.L., Cavanagh R.D., Camhi M., Burgess G.H., Cailliet G.M., Fordham S.V., Simpfendorfer C.A., Musick J.A. (eds.) (2005) Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes IUCN Shark Specialist Group, Status Survey.
4. Hansen M.M., Nielsen E.E., Mensberg, K.L.D. (2006). Underwater but not out of sight: genetic monitoring of effective population size in the endangered North Sea houting (Coregonus oxyrhynchus). Canadian Journal of Fisheries and Aquatic Sciences, 63(4), 780-787.
5. Hoenig J.M., Gruber S.H. (1990) Life-history patterns in the elasmobranchs: implications for fisheries management. pp.1-16. In: J. H. L. Pratt, S. H. Gruber and T. Taniuchi (eds.) Elasmobranchs as living resources: advances in the biology, ecology, systematics and the status of the fisheries, U.S. Department of Commerce, NOAA technical report NMFS 90.
6. Kranenbarg J., Winter H.V., Backx J.J.G.M. (2002). Recent increase of North Sea houting and prospects for recolonization in the Netherlands. Journal of Fish Biology, 61, 251-253.
7. Lythgoe J., Lythgoe G (1991). Fishes of the Sea: The North Atlantic and Mediterranean. MIT Press, Cambridge.
8. Scharpf C. Family Rhinobatidae Bonaparte 1835 (Guitarfishes). The ETYFish Project https://etyfish.org/ETYFish_Rhinobatidae.pdf
9. Secor D., Kerr L. (2009). Lexicon of life cycle diversity in diadromous and other fishes. Am. Fish. Soc. Symp. (69): 537-556.
10. Węsławski J., Furdyna A., Jablonska E. (2024). What is written in the Nature Restoration Law – we explain point by point. Article 5. Marine ecosystem restoration.
11. https://naukadlaprzyrody.pl/wp-content/uploads/2024/04/co-jest-w-nrl-artykul-5-siedliska-morskie.pdf
12. Wueringer B.E.; Squire L. Jr; Collin S.P. (2009). The biology of extinct and extant sawfish (Batoidea: Sclerorhynchidae and Pristidae). Rev Fish Biol Fisheries. 19(4): 445-464.
13. https://www.cms.int/en/species/Mobula-eregoodootenkee
14. https://en.wikipedia.org/wiki/List_of_threatened_rays
15. https://en.wikipedia.org/wiki/List_of_threatened_sharks