Pacific herring | Pacific sardine | Pacific hake |
Spiny dogfish | Sablefish | Lingcod |
Arrowtooth flounder | Pacific halibut | Dover sole |
Rex sole | Petrale sole | Yellowtail rockfish |
Canary Rockfish | Pacific salmon | Pink and sidestripe shrimp |
Killer whales | Humpback whales | Eastern Pacific grey whales |
Other cetaceans | Sea otters | Steller sea lions |
Harbour seals | California sea lions | Northern fur seals |
Marine birds |
Pacific herring (Clupea pallasi)
Pacific herring (Clupea pallasi) are an important target and forage species and are zooplanktivorous, feeding primarily on euphausiids as adults (Wailes 1936). There is a negative relationship between water temperatures and herring recruitment. Warmer water temperatures after 1989 resulted in increased Pacific hake abundance off the WCVI and it is hypothesized that hake have negatively affected the herring population in that area (Ware 1991). Recent evidence also suggests that decreases in prey abundance over time and competition with Pacific sardines may be additional factors affecting WCVI herring survival (Schweigert et al. 2010).
There are two major fishing stocks of Pacific herring that forage off the WCVI in the summer: the WCVI and the Strait of Georgia (SOG) stocks. During 1934-1968, a herring reduction fishery was active, with herring dominating total fish landings during the 1950s-mid-1960s (Schweigert and Fort 1999). The population collapsed in the mid-1960s and was closed to fishing. A roe fishery re-opened in 1972, but closed again when the stock biomasses were below their fishery threshold cutoff: in 1985, 1986, and again during 2006-present for the WCVI stock, and in 1986 for the SOG stock. In winter these fish move to inshore spawning areas, where a roe fishery is operates on age 3 and older fish in the SOG.
Pacific sardine (Sardinops sagax)
Pacific sardine (Sardinops sagax) in BC are part of the northern stock of the Coastal Upwelling Domain of the northeast Pacific (Ware and Thomas 1991) and are important target and forage species. Pacific sardine are a transboundary species spawning at 2-10 years of age off southern California in spring and migrating to Oregon, Washington, and British Columbia during the summer to feed on abundant plankton resources (diatoms, copepods, euphausiids; Emmett et al. 2005). The extent of the northward migration is, in part, related to a combination of oceanographic conditions (McFarlane and Beamish 2001), such as sea surface temperature, such that stocks move further north during warmer years. Sea surface temperature has also been related to juvenile survival for recruitment to the adult spawning population with stronger recruitment occurring during warmer years. Scale-deposition studies have revealed boom and bust cycles of Pacific sardine populations over hundreds of years off California (Baumgartner et al. 1992) and thousands of years off Chile (Valdes et al. 2008). Sardine productivity has been linked to upwelling and its effect on primary and secondary production (Ware and Thomas 1991). Sardine are preyed upon by a variety of fish, bird, and mammals, particularly salmonids, sharks, sea lions, and humpback whales.
A reduction fishery for Pacific sardine operated during 1925-1945 and then failed in 1946 when the population of sardines collapsed (Ware and Thomas 1991). In 1992, sardine were observed in BC waters (Hargreaves et al. 1994) and during 1996-2001, an experimental fishery was conducted. In 2002, a commercial fishery began, consistent with Canadas policy on New and Emerging Fisheries and using a precautionary approach. Since 2007, Canada has developed an annual Integrated Fisheries Management Plan to support this growing fishery, which utilizes purse seine gear in nearshore waters and inlets.
Pacific hake (Merluccius productus)
Pacific hake (Merluccius productus) is distributed throughout the California Current System from Baja California to the Gulf of Alaska. The most abundant BC hake population is a transboundary, coastal stock that inhabits waters around the continental shelf. Hake is an important target and pelagic species off the WCVI. Migratory Pacific hake move into BC waters in the spring and leave in the fall (Beamish and McFarlane 1985). The number of fish that migrate north depends on summer temperatures, with more entering BC waters in warmer years (Ware and McFarlane 1995). In late spring, between 250,000 and 500,000 tonnes (on average) of hake migrate into Canadian waters off the WCVI, feeding in the area until October. Hake in BC waters can impact other species by competing for zooplankton resources (e.g., euphausiids) with other species, such as herring and salmon, or by preying upon species, such as herring (Ware and McFarlane 1995, McFarlane et al. 2001, Tanasichuk et al. 1991).
The temporal and spatial distribution of hake has changed over time. Prior to 2007, 80%-90% of BC Pacific hake were caught off the WCVI, but recently catch locations have shifted northward. Changes in hake distribution may be related to ocean temperatures. Hake prefer warmer water temperatures and are found further north in warm years and further south in cold years. Total hake biomass in U.S. and Canadian waters peaked in the mid-1980s with a lower peak during 2003-2005 (Ianson and Flostrand 2010). The main driver of stock productivity in recent decades is likely recruitment variability (Helser et al. 2009). Large year classes occurred in 1980 and 1984, with other relatively large recruitment events occurring in 1970, 1973 and 1977 (Ianson and Flostrand 2010). The 1999 year class has been the most dominant cohort since the late 1980s and has supported fishery catches since 2002 (Helser et al. 2009).
Picture © NOAA, AFSC, RACE
Spiny dogfish (Squalus acanthias)
Spiny dogfish (Squalus acanthias) are long-lived (up to 80 years), reach lengths of 130 cm, and are distributed from Baja California to the Aleutian Islands in Alaska. They are common in BC waters. Spiny dogfish is a pelagic species distributed over the continental shelf and slope at depths from the surface to 900 m (McFarlane and King 2003). The species is most often found in water depths < 300 m. Tag-recapture studies provide evidence that spiny dogfish undergo extensive migrations with a trans-Pacific connection of spiny dogfish stocks (McFarlane and King 2003). Spiny dogfish fertilization occurs internally and is followed by an extended gestation period (almost two years) after which fully developed pups are born. They are very slow growing and females mature at 35-36 years. The species has low fecundity, with females giving birth to only 6-7 pups per pregnancy. Spiny dogfish are often found in large schools where they feed on pelagic prey such as fish, squid, euphausiids, and ctenophores. They are preyed upon by other sharks and possibly marine mammals.
Spiny dogfish have been commercially caught in BC waters for over 140 years. They were initially exploited as a source of oil and vitamin A. Currently spiny dogfish is captured in the groundfish trawl fishery and targeted in a longline fishery, and is exported as a food product. Recent catches of spiny dogfish have averaged ~1,600 t annually (Galluci et al. 2011). Spiny dogfish were included because of their importance as a target species and a top predator.
Picture © NOAA, AFSC, RACE
Sablefish (Anoplopoma fimbria)
Sablefish (Anoplopoma fimbria) is a highly migratory, long-lived (70+ years), predatory species that resides in pelagic and demersal realms of shelf and slope waters from Central Baja California to the Gulf of Alaska, the Bering Sea, and Japan. Sablefish typically occupy depths greater than 200 m and spawn in January-March at depths greater than 1,000 m. Planktonic larvae are distributed in surface waters over the shelf and juveniles migrate to nearshore areas until they are 2-5 years old, when they migrate offshore. Females mature at 3-5 years of age and reach maximum sizes of ~80 cm with a maximum age of 113 years. Sablefish consume fish (including herring, sandlance, and walleye pollock) as well as euphausiids and squid.
Sablefish sustain lucrative hook and line, and trap fisheries on the WCVI and are, therefore, key target species in this ecosystem.
Picture © NOAA, AFSC, RACE
Lingcod (Ophiodon elongatus)
Lingcod (Ophiodon elongatus) are present on the west coast of North America, from Shumagin, Alaska to Baja, California. Lingcod are abundant off the BC coast (Gordon, 1994) and more specifically from Point Conception, California to Cape Spencer, Alaska. They are found near the seafloor at depths from 3 to 400 m. Lingcod are most commonly distributed over rocky areas at depths from 10 to 100 m on the continental shelf and appear to exhibit some site specificity. In BC waters, spawning begins in December and continues through March with peak spawning activity occurring in late January and early February. Mature females move from deeper water to join males in nearshore spawning grounds in October (King 2001). Male lingcod guard fertilized eggs in nests until hatching. Larvae have a short pelagic stage (lasting a couple of months) before settling to eelgrass beds or flat sandy areas in nearshore areas as juveniles. Lingcod mature at 3-5 years of age and have a maximum age of 25 years. Lingcod prey on a wide variety of fishes and invertebrates and are voracious predators. Lingcod are probably consumed by marine mammals and sharks.
Lingcod in offshore regions are primarily captured in the groundfish trawl fishery. In nearshore areas, recreational fishing targets lingcod although the majority of the catch has been in the groundfish trawl fishery. Lingcod have a long history of exploitation in BC waters and catches have generally been decreasing in recent years due to both management measures and decreases in abundance. Lingcod were included because of their value as a target species and as a top predator.
Picture © NOAA, SWFSC, ROV Team
Arrowtooth flounder (Atheresthes stomias)
Arrowtooth flounder (Atheresthes stomias) inhabit a wide range of depths from 50 to 900 m and prefer water temperatures in a narrow range from 7°C to 8°C (Perry et al. 1994). Juveniles prefer sand and mud substrates, but as adults, they appear to show little preference for substrate type (Perry et al. 1994). Arrowtooth flounder occupy separate winter spawning and summer feeding areas, undertaking a seasonal bathymetric movement from shallower water in summer to deeper water in winter (Ianson and Flostrand 2010). Juvenile arrowtooth flounder feed on small benthic prey such as shrimp, and adults are piscivorous feeding on a number of fish species including: Pacific herring, juvenile walleye pollock, and Pacific sandlance (Perry et al. 1994, Pearsall and Fargo 2007). Adult arrowtooth flounder are an important top predator species in the WCVI ecosystem.
In recent years, arrowtooth flounder has been one of the main catch species in bottom trawl fishing off the WCVI (Workman et al. 2008). The U.S. Gulf of Alaska (GOA) groundfish bottom trawl survey and the BC multispecies bottom trawl survey indicate arrowtooth flounder abundance has increased since the late 1970s (GOA; Turnock and Wilderbuer 2009) and 1990s (BC) and is currently more abundant than it has been in the previous 20 years (Starr and Fargo 2006). Until recently, landings were low due to the poor flesh quality of these fish; however, in 2005 specialist vessels began targeting these species due to an improved market (Starr and Fargo 2006, Ianson and Flostrand 2010) and this species is now managed as a part of an individual vessel quota system.
Picture © NOAA, SWFSC, ROV Team
Pacific halibut (Hippoglossus stenolepis)
Pacific halibut (Hippoglossus stenolepis) are distributed within the North Pacific from California to Alaska and from Japan to Russia. Spawning season is generally from November to March when halibut move from relatively shallow summer feeding areas to deeper waters along the continental shelf (180-450m). Juveniles consume euphausiids and small fish, whereas, adults consume fish, such as herring, sandlance, smelt, walleye pollock sablefish, and rockfish. Larvae drift in the currents for 6 months after spawning; larvae drift to the west in the Gulf of Alaska and to the north into the Bering Sea. Juvenile halibut migrate back to the south and east towards their spawning grounds.
Total Pacific halibut removals from BC waters (all BC waters; IPHC management area 2B) increased in the early 1980s from approximately 2,700 t to 7,000 t in 1988. Removals varied between 5,000 and 6,000 t in the 1990s and were approximately 4,000 t in 2010 (Hare 2010). Projected spawning biomass is expected to increase; however, declines in size-at-age have been noted (Hare 2010). Halibut are a commercially important target species that is associated with bottom habitat. They also provide an important recreational fishery which is allocated 12% of the annual coastwide quota.
Picture © NOAA, SWFSC, ROV Team
Dover sole (Microstomus pacificus)
Dover sole (Microstomus pacificus) range from southern Baja California to the Gulf of Alaska (Mecklenberg et al. 2002). Dover sole inhabit soft sediments at a wide range of depths from 10 m to 1,244 m (Brodziak and Mikus 2000), although adults are most commonly found at depths >300 m. The spawning season for dover sole is protracted and has been estimated to be from at least February to May. Dover sole eggs are pelagic and larvae are thought to be pelagic for almost 2 years before settling as juveniles to the appropriate substrate (Markle et al. 1992). Juvenile fish move into deeper waters with age, and begin the seasonal spawning migration when they reach maturity beginning at age 4-5 years. The maximum age for dover sole is 54 years. Dover sole feed on benthic prey, including brittle stars and polychaete worms. Important predators of dover sole include large piscivorous fish such as halibut and walleye pollock.
Dover sole in BC were last assessed in 1999. The winter bottom trawl fishery has persisted for ~ 40 years, primarily targeting spawning aggregations. Historically, the annual harvest of Dover sole has been ~500-1,000 t. Dover sole were included because of their importance as a target species in the groundfish winter bottom trawl fishery and association with bottom habitat. For more information on their life history, see Love (1996).
Picture © NOAA, SWFSC, ROV Team
Rex sole (Eopsetta exilis)
Rex sole (Eopsetta exilis) range from Southern California to the Bering Sea, and are abundant in BC. Rex sole are primarily found at depths from 100-800 m on the continental shelf and slope. They are most commonly distributed on the continental shelf at depths < 200 m on soft sediments. Rex sole spawn pelagic eggs during a protracted spawning season that can last from September-May. The eggs and larvae are thought to be pelagic for up to a year. The species mature at age 3-5 for males and 5-9 for females (Love 1996), with a maximum recorded age of 27 years (Munk 2001). They primarily feed on benthic prey such as polychaete worms, shrimp and amphipods.
Rex sole are caught in the winter trawl fishery off the west coast of Vancouver Island. Although a small component of the commercial landings, rex sole are captured widely in the groundfish and multispecies trawl surveys. Rex sole were included because of their occurrence as a target species in the groundfish winter bottom trawl fishery and association with bottom habitat. For more information on the life history of this species, see Love (1996) or Mecklenberg et al. (2002).
Picture © NOAA, SWFSC, ROV Team
Petrale sole (Eoposetta jordani)
Petrale sole (Eoposetta jordani) are distributed from Baja California to the Bering Sea (Mecklenberg et al. 2002), however the northern limit of commercial abundance probably occurs in BC. Petrale sole inhabit soft sediments at depths from <50 to 550 m. Petrale sole show a distinct seasonal depth migration, inhabiting shallower depths on the continental shelf (<200 m) in the summer and deeper depths on the continental slope during the winter. The spawning season for petrale sole is protracted and has been estimated to be from November to April. The pelagic egg and larval stages of Petrale sole can last 6-8 months before settlement. Male petrale sole mature at 3-4 years, while females mature at 4-5 years. The maximum age for petrale sole is 35 years. Petrale sole are ambush predators feeding on benthic prey, including fishes such as herring and invertebrates such as crabs. Important predators of petrale sole include large piscivorous fish, marine mammals and sharks.
Petrale sole in BC were last assessed in 1999. Although a target for directed fishing in the past, there is currently no directed fishery for petrale sole in BC due to concerns over decreasing biomass (DFO 1999). Historically, the annual harvest of petrale sole has been as high as ~5,000 t, but is currently less than ~1,000 t. Petrale sole were included because of their past importance as a target species in the groundfish winter bottom trawl fishery and their status as a potentially vulnerable species.
Yellowtail rockfish (Sebastes flavidus)
Yellowtail rockfish (Sebastes flavidus) are distributed from southern California to the central Gulf of Alaska (Love et al. 2002). Yellowtail rockfish are most abundant from California to northern BC. This species is primarily found on the continental shelf at depths from 110-200 m. Little is known regarding the pelagic larval and juvenile stages, but in California, juvenile yellowtail rockfish have been found at shallower depths than adults. Spawning is believed to occur during the winter in BC. Maturity occurs at ~14 years in BC waters and the maximum age of this species is believed to be ~65 years. Yellowtail rockfish are semi-pelagic and occur over rocky substrate. They generally remain within 25 km of a site, but have been found to travel up to 400 km or more (Stanley et al. 1994). They primarily consume planktonic prey from the water column (copepods and euphausiids) and can occur in patchy, dense schools, oftentimes with other semi-pelagic species. They are probably consumed by lingcod, other large piscivores and fish-eating marine mammals.
In BC, yellowtail rockfish are caught in the commercial groundfish trawl fishery and the hook and line fishery, with average annual catches of ~3,300 t. Much of the catch is taken as bycatch in fisheries directed at other rockfish species as well as in hake fisheries. Yellowtail rockfish were included because of their importance as a target species and as a habitat-linked species. This species was last assessed in 1998, therefore no recent status is available. For more infos see Love et al. (2002).
Picture © NOAA, AFSC, RACE
Canary Rockfish (Sebastes pinniger)
Canary rockfish (Sebastes pinniger) are found from the western Gulf of Alaska (Shelikof Strait) to northern Baja, California (Love et al. 2002). Populations are most abundant between BC and northern California. Adult Canary rockfish are found at depths from 100-225 m on the outer continental shelf, with peak abundances near 150 m. Spawning of live larvae occurs during the winter and is followed by a relatively short pelagic stage of 3-4 months. Juvenile stages settle in shallower waters (less than 100 m), but are not well studied. Canary rockfish mature at ~13 years in BC and are long-lived with a maximum age near 100 years. Canary rockfish, like yellowtail rockfish, are primarily semi-pelagic schooling fishes that occur over rocky habitat. They primarily feed on planktonic prey (copepods, euphausiids and small fish). They are probably consumed by lingcod, other large piscivores and fish-eating marine mammals.
In BC, Canary rockfish are primarily captured in the groundfish trawl fishery and the hook and line fishery (Stanley et al. 2009). Historically, this catch has averaged ~900 t annually. Minor catches occur in the salmon troll fishery, First Nations fisheries and recreational fisheries. The Canary rockfish was assessed as Threatened by COSEWIC in 2007. Canary rockfish were included because of their importance as a target species, a habitat-linked species and a vulnerable species. For more infos see Love et al. (2002).
Picture © NOAA, AFSC, RACE
Pacific salmon (Oncorhynchus sp.)
Five species of anadromous Pacific salmon occupy the WCVI waters at some point during their life cycle: chinook (Oncorhynchus tshawytscha), coho (O. kisutch), sockeye (O. nerka), chum (O. keta), and pink (O. gorbuscha) salmon (DFO 2011a). Salmon migrate to rivers and streams to spawn during spring - fall (timing varies with species). Adults die after spawning; eggs hatch and the young remain in freshwater for varying lengths of time (depending on the species) before going to sea for 1 to 5 years (dependent on species and life history type) to feed. In the ocean, chinook and coho salmon generally eat small fish, whereas, sockeye and pink salmon consume zooplankton (e.g., euphausiids; DFO 2011a).
The numbers of salmon that return varies annually and decadally (DFO 2011a). There is some evidence of improved marine survival during cold years (e.g., La Nina years) compared to warm years (Hyatt and Luedke 1999). The survival of sockeye salmon stocks that enter continental shelf areas with stronger oceanic influences, (i.e., Barkley Sound sockeye in the WCVI), appears to be related to alternations in La Nina-like and El Nino-like conditions (Hyatt and Luedke 1999).
Sockeye, chinook, coho and chum salmon are harvested on the WCVI, however, there are currently no WCVI pink salmon fisheries. Salmon are harvested by First Nations, commercial, and recreational sectors and are consumed by large predators, such as resident killer whales, therefore, they are both target and charismatic species. For more information on salmon management and population status see the salmon integrated fishery management plan available below.
Pink and sidestripe shrimp
Six species of pandalid shrimp are targeted by commercial fisheries along the BC coast. On the WCVI, smooth pink shrimp (Pandalus jordani) and sidestripe shrimp (Pandalopsis dispar) are the most important species caught (Ianson and Flostrand 2010). Shrimp biomass estimates vary annually but were generally high in the late 1970s and in the early 2000s. To date, research has indicated that no single environmental factor or group of factors have been identified that can account for the interannual variability in shrimp abundance (Ianson and Flostrand 2010).
Shrimp are an important target and habitat-linked species off the WCVI. Both Canadian and U.S. commercial shrimp trawl vessels caught shrimp until the late 1970s, when industry and government reduced fishing fleets and Canada instilled the EEZ. Ianson and Flostrand (2010) state that Recent efforts to manage shrimp fishing include seasonal constraints and by-catch reduction strategies. Total annual shrimp landings varied little during 1997 - 2001 (approximately 1,000-1,300 tonnes) but in subsequent years, total catches declined below 450 t, mainly due to economics of the industry (D. Clark pers comm.).
Picture © NOAA, AFSC, RACE
Killer whales
Killer whales are an important top predator, charismatic, and also a vulnerable species. Ianson and Flostrand (2010) state: There are three distinct ecotypes of killer whales in BC; the transients, residents, and offshore killer whales. The resident killer whales are further divided into two unique populations; the northern residents and southern residents. All ecotypes are listed under Canadas Species at Risk Act (SARA). Transients and northern residents are listed as threatened, southern residents are endangered and offshore killer whales are a species of special concern1.
Canadas 2008 COSEWIC status report for killer whales states that in 2006 there were 244 northern resident killer whales, 87 southern resident killer whales, and approximately 243 transients. Research efforts from 1988 to 2008 recorded a total of 288 offshore killer whales in BC, which is considered a conservative estimate (COSEWIC 2008). All three ecotypes utilize coastal waters off WCVI, however sightings of offshore killer whales have been rare. Threats to killer whales include limited food availability, bioaccumulation of toxins (e.g. PCBs), and disturbance (Ford et al. 2010). Each ecotype is a prey specialist. Resident killer whales (northern and southern) feed exclusively on chinook and chum salmon, while transients feed on marine mammal species. The feeding ecology of offshore killer whales is less well understood, but preliminary information suggests they may specialize in predation on elasmobranchs.
Picture © Chris Rooper, NOAA, AFSC
Humpback whales
Humpback whales are charismatic and vulnerable species. Ianson and Flostrand (2010) state: North Pacific humpback whales are listed as a threatened species under SARA. Despite being hunted to near extinction early in the previous century, the number of North Pacific humpback whales in BC waters has been gradually increasing over the past decade (annual BC population growth rates estimated to be 3%-6%) and conservative estimates of humpbacks off the WCVI in foraging periods between May and October are 200-250 animals (Ford et al. 2009). Humpback whales use coastal waters off WCVI to feed and as migration routes to higher latitude feeding areas in northern BC and Alaska. Humpbacks are known to feed on sardine, herring and euphausiids while in BC waters. Several long-term critical feeding habitats in BC have been identified for humpbacks, including a 6,188 km2 area off WCVI which extends from shore out to the continental shelf (Nichol et al. 2010). As with killer and grey whales, food limitation is considered a threat to humpback whales, as are entanglement and vessel collision.
Eastern Pacific grey whales
In spring, eastern Pacific grey whales migrate from subtropical Mexican breeding grounds, through WCVI waters, to their primary feeding grounds in the Bering, Chukchi and Alaskan Beaufort Seas. Ianson and Flostrand (2010) state: A small proportion of this population (approximately 80; Calambokidis et al. 2002) remains in areas off WCVI to feed throughout the summer and early fall (Calambokidis et al. 2002). These summer residents show fairly high site fidelity to feeding locations (e.g. Barkley Sound), and many individuals revisit the same feeding location year after year. In BC, summer resident grey whales are known to feed on herring spawn, crab larvae, amphipods, and mysid and ghost shrimp (DFO 2010a). Given their wide variety of prey species, summer resident grey whales exploit almost all types of near-shore marine habitats and are found along the entire WCVI.
Grey whales were severely depleted during 19th century commercial whaling. In 2005, they were listed as a species of special concern under SARA. The grey whale population appears to be increasing. In 1994, the Eastern Pacific grey whale was de-listed from the U.S. Endangered Species Act based on evidence the population was nearing its estimated historic population numbers. The recent and best estimate of the Eastern Pacific grey whale population suggests that they are approaching the current estimated carrying capacity (Rugh et al. 2005, 2008). Grey whales, like killer whales and humpback whales are charismatic species off the WCVI.
Other cetaceans
Ianson and Flostrand (2010) state: Other large baleen whales sometimes visit the waters off WCVI; blue, fin, sei, and the extremely rare North Pacific right whales. These whales feed on a variety of euphausiids, copepods and forage fishes. These large whales are vulnerable to collisions with boats, noise, pollution and entanglement in lost or active fishing equipment (Gregr et al. 2006), and reduced food availability (COSEWIC 2002). Blue, sei and North Pacific right whales are endangered species, while fin whales are listed as a threatened species under SARA.
Smaller cetaceans are also present in WCVI waters, but there are few data on abundance and none show trends in populations. Examples are Dalls porpoises, Pacific white-sided dolphin and Pacific harbour porpoises. Harbour porpoises are a species of special concern under SARA and a management plan has been developed to address knowledge gaps and threats to this species (SARA 2005).
Sea otters (Enhydra lutris)
Ianson and Flostrand (2010) state: The sea otter (Enhydra lutris) historically occupied the coastal zone of the North Pacific from Northern Japan to Baja California Mexico, but was hunted intensively for its fur (from about the 1700s to the 1900s) and extirpated throughout much of its global range by 1911. 89 sea otters were reintroduced to Checleset Bay, WCVI from Alaska between 1969 and 1972 and, following successful re-establishment, the population has increased and re-established some of its range, so that it covers the northern coast of Vancouver Island extending southward to approximately Tofino, currently occupying about 25%-33% of their historical range (COSEWIC 2007).
Sea otters forage primarily on invertebrates, which they obtain by diving to the sea floor. The seaward extent of their habitat is, therefore, limited by their diving ability. Most foraging dives are in depths of less than 40m, thus, sea otters seldom range beyond 1-2km of shore (COSEWIC 2007). In coastal BC, sea otters generally occur along stretches of exposed coastline characterized by complex rocky shorelines with small islets and offshore reefs.
Most foraging takes place in subtidal areas, but foraging also occurs in the intertidal zone at high tide (Sea Otter Recovery Team 2007). In recently re-occupied rocky habitats, where sea urchins are abundant, urchins are consumed preferentially, probably because of ease of capture. As the quantities of their most readily obtainable (and preferred) prey items decline, the diet of sea otters diversifies to include a larger array of invertebrates, such as bivalve clams, snails, chitons, crabs and sea stars (Estes et al 1981). In soft sediment habitats, sea otters forage on clam species such as butter clams, horse clams and geoduck clams through excavation (Sea Otter Recovery Team 2007).
Sea otters are relatively sedentary, occupying small overlapping home ranges on the order of 10s of kilometres of coastline. Sea otters form resting aggregations called rafts that can number over a hundred individuals. Rafts often form habitually, in the same locations over periods of years. Males and females occupy spatially distinct areas, so that there are male rafts and female and pup rafts occupying different areas (Nichol et al 2005).
Sea otters are a charismatic and vulnerable species associated with a particular type of habitat. Ianson and Flostrand (2010) state: In Canada, sea otters were down-listed to Special Concern under the Species at Risk Act in 2008. The species is protected under the Fisheries Act and by provisions in the British Columbia Wildlife Act.
Steller sea lions
Steller sea lions are year-round residents of BC waters and are listed as a species of special concern on Schedule 1 of the SARA. Breeding animals spend the spring and summer on breeding sites and then, in August-September, disperse and occupy winter haulout sites in protected waters (DFO 2010b, Olesiuk 2009). Non-breeding animals are found at year-round haul-out sites on the outer, exposed coast (DFO 2010b). Survey counts indicate that local breeding populations of Steller sea lions in BC have been increasing at a rate of 3%-4% per year (DFO 2010b) since the mid-1960s. The increase in Steller sea lion abundance is partly attributable to recovery from hunting and predator-control programs, but in recent years populations have exceeded peak historic levels.
Steller sea lions are also a top predator species. During the summer breeding season, the Steller sea lions prey on forage fish (mainly herring, sand lance and sardine), gadids (mainly hake), salmon, rockfish, flatfish and other prey (Trites and Olesiuk, unpubl. data). During non-breeding season, primary prey includes forage fish (mainly Pacific herring and sardine), gadids (mainly Pacific hake and walleye pollock), dogfish, salmon, squid and octopus, eulachon, sandlance, and lingcod (Olesiuk 1988, DFO 2008).
Harbour seals
Harbour seals are year-round residents of coastal BC waters (DFO 2010c). They are primarily distributed within 20 km of shore (DFO 2010c). This species was also subject to predator control programs and commercial harvest. As a result their numbers were depressed before they were protected under the Fisheries Act in 1970 (Olesiuk 1999). During the 1970s and 1980s populations increased exponentially (DFO 2010c), and the population appears to have now stabilized, suggesting the population has reached carrying capacity at near-historic levels (DFO 2010c). Harbour seals are top predators and have a similar diet as Steller seal lions and they typically forage within 10-20 km of haulout sites (DFO 2010c).
California sea lions
California sea lions are found in BC waters primarily in winter months and are not year-round residents, as they migrate south to breeding areas in California and Mexico. Expansion of the California sea lion distribution into BC waters in the 1960s is likely the result of recovery in southern portions of their range as well as changing ocean conditions and fluctuations in local prey abundance (Olesiuk and Bigg 1988). California sea lion counts in BC waters increased from a few hundred animals in the 1970s to 1,500 in the 1980s (Bigg 1985). Counts peaked at 4,500 animals in 1984 and then stabilized at approximately 3,000 animals (Bigg 1985). Since then, the counts have fluctuated between 1,000 and 3,000 animals (Olesiuk, pers. comm.). California sea lions are top predators in BC and feed primarily on Pacific herring (35% of their diet), Pacific hake, walleye pollock, dogfish, and some salmon (10% of their diet; Olesiuk 1988).
Northern fur seals
Northern fur seals are highly migratory and approximately 1/3 of the North Pacific population (~375,000 animals) winters off the coast of North America (DFO 2007b). Approximately 1/3 of this overwintering group of animals (~125,000 animals) resides in coastal BC waters for approximately 3 months at some point during December-May, with a peak abundance in May (Olesiuk 2008a, DFO 2007b). Females comprise the majority of animals and their main wintering area in BC is the La Perouse Bank off of the southwest coast of Vancouver Island (DFO 2007b). The abundance of northern fur seals in the Pacific has decreased over the last 30 years and is a conservation concern (DFO 2007b). This decrease in the North Pacific population has occurred on the Pribilof Islands, Alaska, the cause of which is not known. Abundance on other rookeries has been stable or increasing.
Northern fur seals are important top predators in waters off WCVI. Northern fur seal diet varies by season and region, but stomach samples collected during 1958-74 indicate that overwintering animals in BC waters primarily forage on Pacific herring and squid (DFO 2007b, Perez and Bigg 1986). Other important prey items noted in stomach samples collected at various times and locations during January-June, 1958-1974 included walleye pollock, sablefish, and salmonids (Perez and Bigg 1986).
Marine birds
Marine birds are top predators and some species are considered vulnerable. Ianson and Flostrand (2010) state: Seabird species are generally long-lived, with very low-reproductive output (usually one egg) per year, and late onset of sexual maturity. The population dynamics of seabird species are particularly sensitive to changes in adult mortality because of their life history strategies, which are remarkably similar among species, and because population recovery is relatively slow. Severe weather and climate change are common natural threats. Ship-source oil pollution (Butler et al. 1988, Camphysen and Heubeck 2001, Wiese and Robertson 2004), fisheries bycatch (Smith and Morgan 2005) and introduced predators to breeding colonies (Moors and Atkinson 1984) are probably the largest anthropogenic threats to seabird populations worldwide. Seabird breeding success is tied closely to the availability of key prey species and can vary widely between years (DFO 2007b). Since 1994, researchers from the Centre for Wildlife Ecology have visited Triangle Island (northern tip of Vancouver Island) to collect time-series data on seabirds.
In general, breeding success declined for many seabirds, reaching an all-time low in 2007 (e.g. Cassins auklet and rhinoceros auklet). This poor success was contrary to predictions based on the cool sea surface temperatures that occurred during this time period. The preferred prey species for Rhinoceros auklet nestlings (Pacific sandlance) was extremely low in 2007. It made up >10% of the birds diets that year (Hipfner 2008). The common murre also had the lowest measured success rate in 2007, but that time series only started in 2003 (ibid.).
