192 Arctic Biodiversity Assessment Anadromous (sea-run) male northern Dolly Varden Salvelinus malma malma from the Babbage River, Yukon Territory, Canada in pre-spawning coloration; this salmonid is adapted to Arctic riverine habitats in Beringia. Photo: Neil Mochnacz, Fisheries and Oceans Canada. 193 Chapter 6 Fishes Lead Authors Jørgen S. Christiansen and James D. Reist Contributing Authors Randy J. Brown, Vladimir A. Brykov, Guttorm Christensen, Kirsten Christoffersen, Pete Cott, Penelope Crane, J. Brian Dempson, Margaret Docker, Karen Dunmall, Anders Finstad, Vincent F. Gallucci, Johan Hammar, Les N. Harris, Jani Heino, Evgenii Ivanov, Oleg V. Karamushko, Alexander Kirillov, Alexandr Kucheryavyy, Hannu Lehtonen, Arve Lynghammar, Catherine W. Mecklenburg, Peter D.R. Møller, Tero Mustonen, Alla G. Oleinik, Michael Power, Yuri S. Reshetnikov, Vladimir I. Romanov, Odd-Terje Sandlund, Chantelle D. Sawatzky, Martin Svenning, Heidi K. Swanson and Frederick J. Wrona Contents Summary ..............................................................194 6.3. Marine fishes in the Arctic Ocean and adjacent seas ���������������217 6.1. Introduction .......................................................195 6.3.1. Distribution and zoogeography ..............................218 6.3.2. Status of knowledge ........................................219 6.2. Freshwater and diadromous fishes of the Arctic and sub-­Arctic ...195 6.3.2.1. The roots of Arctic ichthyology �����������������������219 6.2.1. Focus of this section .........................................195 6.3.2.2. Uses and abuses of fish data from the AOAS ..........219 6.2.1.1. Overview of northern freshwater and diadromous 6.3.2.3. Arctic-Antarctic comparisons ������������������������221 fish diversity .........................................196 6.3.3. Regional considerations .....................................222 6.2.1.2. Geographic scope ..................................197 6.3.4. Species richness and zoogeographic patterns ...............223 6.2.2. Diversity of freshwater and diadromous fishes in the Arctic ...198 6.3.4.1. Species richness ....................................223 6.2.2.1. Overall biological diversity of freshwater and 6.3.4.2. Species-area relationships ...........................224 diadromous fishes ...................................198 6.3.4.3. Rare and disjunctive taxa ............................224 6.2.2.2. Faunistic scope – diversity among families ...........200 6.3.4.4. Zoogeographic patterns ����������������������������226 6.2.3 Patterns of diversity at the species level .......................200 6.3.5. Prominent fish taxa .........................................228 6.2.3.1. Arctic diversity within fish families relative to global diversity ......................................200 6.3.5.1. Top 10 species-rich families ..........................228 6.2.3.2. Spatial patterns of freshwater and diadromous 6.3.5.2. Arctic cods ..........................................228 fish diversity .........................................201 6.3.5.3. Cartilaginous fishes .................................228 6.2.4. Zoogeography of particular taxa ............................204 6.3.6. Status and trends ............................................229 6.2.5. Other diversity issues in northern fishes ......................205 6.3.7. Drivers and prospects .......................................230 6.2.6. Areas of high diversity, endemism or other significance .......206 6.3.7.1. Functional biodiversity ..............................230 6.2.6.1. Hotspots ............................................206 6.3.7.2. Climate change .....................................231 6.2.6.2. Endemism ..........................................206 6.3.7.3. Human intervention .................................232 6.2.6.3. Significant areas ....................................207 6.3.8. Conclusions and possible conservation actions ...............235 6.2.7. Taxonomic diversity within families ..........................208 6.3.8.1. Key knowledge gaps ................................235 6.2.8. Importance of biodiversity of Arctic freshwater and 6.3.8.2. Other key messages .................................236 diadromous fish .............................................209 Acknowledgements ...................................................236 6.2.8.1. Ecosystems .........................................209 References .............................................................236 6.2.8.2. Relevance to humans ................................210 6.2.9. Drivers, stressors and threats to Arctic freshwater and diadromous fishes ...........................................211 6.2.9.1. Vulnerabilities of freshwater fishes in the Arctic .......211 6.2.9.2. Stressors and threats ................................212 Local indigenous fishermen from Pokhodsk and 6.2.10. Present status and trends ...................................214 » Nutendli report that muksun Coregonus muksun (a fresh­ 6.2.10.1. Trends .............................................215 water fish) amounts have decreased. Fyodor Innoken­ 6.2.11. Gaps and issues ............................................216 tyevich Sokorikov, former head of the fishing sovhoz 6.2.12. Conclusions and recommendations ........................216 6.2.12.1. Conclusions .......................................216 in Pokhodsk reports that muksun was caught in the 6.2.12.2. Recommendations .................................217 amounts of 1,500 tonnes annually in the 1980s but says that in late 1980s and early 1990s there was overfishing of muksun and that is why it has collapsed now. Mustonen 2007. 194 Arctic Biodiversity Assessment SUMMARY unglaciated during the last ice age (i.e. much of Siberia and Beringia; see Fig. 2.2 in Payer et al., Chapter 2), Having occupied Earth’s waters for about five hun- declining to low levels in the eastern Canadian Arctic dred million years, fishes are the oldest group of living and Greenland that were deglaciated last and still retain vertebrates. Fishes have radiated to occupy most aquatic large ice sheets. Time lines are too short and monitored habitats on the planet, and estimates of total biodiversity sites too few to document temporal trends in species di- range from 28,000 up to about 35,000 species. Fishes versity in the Arctic. However, recent evidence suggests are associated with both marine and freshwater habitats, northward colonizations by freshwater fishes along river and some migrate between these biomes. Globally, about corridors and diadromous species into marine environ- 16,000 species occupy marine waters, 12,300 are found ments where climatic constraints have recently de- in fresh waters, and 225 use both habitats during their creased. At present, no documented local extirpations lives. It is within this global diversity context that the or extinctions of taxa are known in the Arctic, although diversity of Arctic fishes must be assessed. local population declines have occurred. Anthropogenic stressors are increasing in importance as risk factors Freshwater fishes are those confined to low salinity both locally and throughout the Arctic. Local ‘hotspots’ aquatic habitats; diadromous fishes are those which of diversity and several globally significant water bodies regularly migrate between fresh and marine waters. The are present. latter occur as two major groups – anadromous fishes spend much of their lives in marine waters migrating Arctic freshwater and diadromous fishes are of particu- to fresh water to reproduce, and catadromous fishes do lar importance to humans both inside the Arctic and the converse. Anadromous fishes constitute the majority elsewhere. Food fisheries by indigenous peoples (i.e. of diadromous fishes in the Arctic. Between 17 and 19 subsistence fisheries) are extensive throughout the Arctic families (3-4% of 515 worldwide) of freshwater and dia- and historically always have been. dromous fishes occur in Arctic waters with about 123- 127 recognized species (1% of 12,547 extant freshwater Pervasive stressors such as climate change result in and diadromous species globally). Many of these taxa are significant and rapid habitat alterations (indirect effects) unresolved species complexes, consist of multiple types as well as direct effects (e.g. thermal stresses) which that have differentiated in separate glacial refugia and/ challenge these fishes. Productivity shifts associated or exist as multiple life history and/or ecophenotypic with climate change may create new opportunities (i.e. forms. All these forms tend to function as, and may be increased population sizes, growth potential) for fresh- the equivalent of, taxonomic species. Accordingly, an water and diadromous fishes. estimate of simple parameters such as species richness and taxonomic and phylogenetic diversity is fraught with Localized stressors (e.g. fisheries, hydrocarbon develop- problems and generally under-estimates the true diver- ment, industrial activities, mining, water withdrawals, sity present. To facilitate this, we will use the upper esti- hydroelectric dams) affect populations either directly mate (127 species) herein. (fisheries) or through habitat impacts. Five families (salmonids – 50+ species of chars, white- Marine fishes reproduce and spawn in seawater although fishes (sensu Coregonus), salmons; cyprinids – 25 min- juveniles and adults may occur also in the low salinity nows; cottids – nine sculpins; percids – eight perches; waters of fjords, coastal areas and river deltas. Here, we and petromyzontids –