INTRODUCTION TO THE MARINE FISHES OF BRITISH COLUMBIA

by

Eric Taylor

Professor, Department of Zoology, University of British Columbia

Director,  Beaty Biodiversity Museum

The Diversity of BC's Marine Fishes

Canada has about 1,100 marine species of fishes spread across the Atlantic, Arctic, and Pacific regions. The Pacific Basin contains approximately 371 purely marine fishes (i.e., those that do not enter freshwater). Several other species (at least 20) occur in adjacent marine waters of Alaska and Washington State and 25 or so occur both in marine and fresh waters (e.g., Pacific salmon).

Marine fishes of BC comprise about 106 families (compared to 15 in freshwater habitats) with representatives from the deepest splits in the vertebrate evolutionary tree (hagfishes and lampreys) to the most derived lineages (Ocean sunfishes, Molidae, and flatfishes, Pleuronectidae). The well-known rockfishes (Sebastes) are contained in what is probably the most diverse family, the mail-cheeked fishes or the Scorpaenidae, with about forty species in BC waters and several families have only single species known from BC waters (e.g., ratfishes, Chimaeridae and the Pearleyes, Scopelarchidae).

The Origins and Biogeography of Marine Fishes

Tracing the origins of the first marine fishes of BC is much trickier than for our current assemblage of freshwater fishes owing to the much greater antiquity of marine waters (all our freshwater habitats were glaciated until about 10,000 years ago – see An Introduction to the Freshwater Fishes of BC). Indeed, some of what are now freshwater environments in BC used to be marine environments! For instance, an assemblage of clearly marine fishes is known from the early Triassic Period (some 250 million years ago – see Schaeffer and Mangus 1976) that included some ancient shark-like fishes from an area around what we now know as the Wapiti Lake area of northeastern BC. More recently, our marine fauna was less directly influenced by the many Pleistocene glaciations, but nearshore marine areas dried-up (owing to sea level declines at the height of glaciation) and surface water temperatures dropped  by several degrees which would have influenced the distribution of many nearshore marine fishes. Postglacial flooding of the nearshore environnment created new habitats, such as the Salish Sea, into which marine fishes, that survived glaciation further offshore or north and south of the icesheets, dispersed creating our current fauna.

Given the greater connectivity and generally larger size of marine, particularly offshore, habitats, the tendency to subdivide the marine realm into biogeographic or ecological zones has been less well-developed, or perhaps less well-accepted than in the freshwater realm. Consequently, the BC coast is at present considered to consist of a single ecozone: the Marine Pacific Ecozone (e.g., see http://ecozones.ca/english/zone/). Clearly, such a vast area described as a single “ecozone” is probably inadequate as environmental differences occur with depth, from offshore to inshore (including up our 80 or so coastal inlets or fjords), from north to south, and in geographically complex areas such as the Georgia Depression. Although as yet not well understood, there are surely major differences in fish species distributions or attributes of single species that are associated with environmental differences within the Marine Pacific Ecozone.

The Conservation of BC's Marine Fishes

The Conservation of BC’s marine fishes takes many forms, from academic studies on persistence of particular species, to programs and regulations overseen by the Federal Department of Fisheries and Oceans to the great work done by many non-profit and non-governmental organizations. The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) and the federal Species and Risk Act (SARA) are the primary ways in which marine fish species are assessed as being Extinct or at some risk of extinction (Extirpated, Endangered, Threatened, or Special Concern - COSEWIC) and for subsequent listing and recovery action –SARA). As of October 2014, 15 BC species of marine (or anadromous – those that feed in the ocean, but return to freshwater to spawn) fishes have been assessed by COSEWIC as being at some level of risk (e.g., several rockfishes and salmon populations - see http://www.cosewic.gc.ca/eng/sct0/rpt/csar_e.htm), but few of these species have as yet been legally listed under SARA. The major factor contributing to at risk status for marine fishes is overexploitation in various fisheries (in contrast to freshwater fishes where habitat loss and degradation is the leading cause of at risk status). Although at risk status driven by overexploitation (as well as habitat loss and damage) is fairly well known and can, at least in theory, be easily addressed, the effects of climate change on the distribution and persistence of BC’s marine fishes is largely unknown.

References

Schaeffer, B. and M. Mangus. 1976.  An early Triassic fish assemblage from British Columbia. Bulletin of the American Museum of Natural History 156: 515-584.

 

Eric Taylor teaches a course at the University of British Columbia on Diversity and Evolution of Fishes.  Read more here.