The Dogfish

Spiny dogfish are a remarkable fish Feeding on plankton as Pauly would wish. Gluttony is a sin that is not on their souls, And they grow so slowly they become very old. Babies arrive all ready to play After living in their moms for two years less a day. Peaceful in life, they avoided confrontation Until humans arrived with merciless exploitation. Stewardship and respect was not in our game As we fished and destroyed without any shame. It is amazing how people with advanced education Could plot or ignore attempts at extermination. But citizens’ concerns have given dogfish rights, So it is now up to us to finish this poem.

Beginning a scientific article with an amateur poem may be highly unusual, but it draws one’s attention to the highly unusual lack of attention paid to spiny dogfish Squalus acanthias by the stewards of our marine ecosystems. A general understanding of the biology of dogfish has been summarized in some excellent publications (Ford 1921; Bonham 1954; Ketchen 1975, 1986). Although the basic biology is known, there is no clear understanding of dogfish ecology. This is surprising considering the species’ current and historical importance to the commercial fisheries. In 2002, dogfish in the commercial fishery averaged Can$0.66/kg ($0.30/ lb); compare this to $1.29/kg ($0.59/lb) for Pacific cod Gadus macrocephalus, $0.34/kg ($0.15/lb) for pink salmon Oncorhynchus gorbuscha, or $1.93/kg ($0.88/lb) for lingcod Ophiodon elongatus. It is clear that the commercial value of spiny dogfish justifies more research to improve our understanding of the processes that regulate its production. Their long life, late maturity, 

   Their long life, late maturity, and slow growth mean that most spiny dogfish in the current commercial fishery were born before the mid-1970s and that individuals born now will be fished from about 2025 to 2050. (This also means that decisions we make today will be relevant through to the end of this century.) Consequently we must look back 20–50 years to understand the factors that produced the current exploitable biomass. Ketchen (1986) reviewed the history of spiny dogfish management, and in this report we review his summary. Our viewpoint is that history has not Beamish et al. 2 been respectful of dogfish either as a species or as an animal sharing a common ecosystem. The reader is referred to Ketchen (1986) for his detailed account of the dogfish fishery, which was the largest fishery in British Columbia in 1944 (Figure 1) and the fourth largest in Canada. Since 1986, the catch of spiny dogfish has been relatively stable at approximately 5,000 metric tons (mt) per year. Approximately 30% of this catch is from the Strait of Georgia. Dogfish quotas of 15,000 mt (offshore stock) and 3,000 mt (Strait of Georgia stock) for Canadian Pacific waters have remained unchanged since the early 1980s. In 2000, total landings averaged less than 5,000 mt, of which 1,200 mt came from the Strait of Georgia. Longline catches in the strait account for over 95% of the landings.

The Sailfin catfish

     Three species of sailfin catfishes (Pterygoplichthys) native to South America, P. multiradiatus, P. pardalis and P. disjunctivus, have been collected recently in several countries in southeastern Asia. Pterygoplichthys multiradiatus is known to reproduce in Taiwan, and P. pardalis is presumed to be reproducing in Singapore given the frequency of its collection and the range in size of specimens collected. The status of the species elsewhere in southeastern Asia is less certain. These catfishes are common in the pet trade and almost certainly were released by aquarists. It is likely that these fishes will become widely established in southeastern Asia and will have negative environmental impacts, including alteration of food webs, in nonnative areas. 

   sailfin catfishes found in Indonesia as Pterygoplichthys pardalis. Specimens in the Zoological Reference Collection, Raffles Museum of Biodiversity Research (ZRC), and the Florida Museum of Natural History (UF) document the presence of Pterygoplichthys pardalis in Singapore, Peninsular Malaysia, Java and Sumatra, and Pterygoplichthys disjunctivus in Singapore, Java and Taiwan (see Material Examined). With about 80 genera and 680 species (Reis et al., 2003), Loricariidae is the largest family of catfishes (Siluriformes). Loricariids are endemic to South America and Panama and are characterized by having large bony plates and a ventral mouth. Loricariids with 10 or more dorsal fin rays are members of the genus Pterygoplichthys and are referred to as sailfin catfishes. All specimens of Pterygoplichthys from southeastern Asia lack an elevated supraoccipital process and have the supraoccipital bone bordered posteriorly by three scutes. 

       A group of four closely related species of Pterygoplichthys share these traits (Weber, 1991, 1992): P. multiradiatus, P. anisitsi, P. disjunctivus, and P. pardalis. Among these species, only P. anisitsi has light spots on a dark background, and only P. multiradiatus has a pattern of uncoalesced dark spots on a light background. Pterygoplichthys disjunctivus and P. pardalis possess a dorsal pattern of coalesced dark spots on a light background. Pterygoplichthys disjunctivus differs from P. pardalis in having dark spots on the venter coalesced to form a vermiculate pattern (Fig. 1); in P. pardalis the venter is covered with discrete spots (Fig. 2). Specimens at ZRC and UF are easily identified as P. pardalis and P. disjunctivus.

The Killifish

       Aplocheiloid killifishes, a diversified group of primary freshwater fishes occurring in tropical and subtropical regions of the Americas, Africa and south-eastern Asia, have been the focus of debates among biogeographers using dispersal and vicariance approaches. The aim of the present paper is to infer biogeographical events responsible for the present distribution of aplocheiloid killifishes using an event-based methodology (DIVA) in conjunction to a phylogeny combining mitochondrial DNA sequences and morphology. Optimal ancestral reconstructions support vicariance events chronologically congruent to northern Gondwana break-up, including separation of Madagascar, India, South America and Africa plates (about 121 –84 Ma), as well as congruent to paleogeographical events within the Africa plate, such as the widening of the Benue Trough (about 90–80 Ma) and the start of activity of the East African Rift System (about 30 Ma), and within the South American plate, as the formation of Gaarland (about 35 –33 Ma), uplift of the Andean Eastern Cordillera (11.8 Ma) and the interruption of the paleo-Amazonas river basin by the uplift of the Vaupés Swell (about 11 – 7 Ma). The reconstructions also support geodispersal events related to the colonization of the Greater Antilles (about 35–33 Ma) and Central America areas (3.7–3.4 Ma) by aplocheiloids through land connections, besides some dispersal events through the Zaire, East Africa, Amazon and Eastern Brazil areas.

      The killifish suborder Aplocheiloidei comprises a diversified clade of small teleosts, usually about 25–50 mm of total length as maximum adult size, with over 620 species occurring in shallow freshwater or rarely brackish environments. Aplocheiloids are mostly known by many included species being popular aquarium fishes, but some of them are also often used as experimental animals in laboratories (e.g., Harrington & Kallman, 1968; Wourms, 1972; Park & Kim, 1984). However, the suggestive geographical distribution of the three families contained in the suborder, with Aplocheilidae endemic to Madagascar, Seychelles, and south-eastern Asia, Nothobranchiidae endemic to sub-Saharan Africa, and Rivulidae endemic to Middle and South America (Costa, 2004),

       has brought the Aplocheiloidei to the focus of debates involving conflicting explanations about patterns of historical biogeography in the tropics (Lundberg, 1993; Murphy & Collier, 1997; Briggs, 2003; Sparks & Smith, 2005). Biogeographical relationships among aplocheiloid lineages were first discussed just after Myers (1931) formally recognising the killifish group presently known as the suborder Aplocheiloidei. Myers (1938), when noticing the possible closely relationships among some South American and African aplocheiloid taxa, claimed that trans-continental distribution of aplocheiloids could not be viewed as evidence of an ancient connection between South America and Africa, since those fish lineages.

The Beluga Sturgeon Fish

      Beluga sturgeon (Huso huso) have inhabited the earth for more than 100 million years. During the past 20 years their numbers have declined by 90%, plummeting to the lowest population sizes ever recorded. This drastic decline has created much controversy as to whether harvest and trade of this species should continue. The situation is further complicated by management that varies among countries sharing the same resources, international trade, and altered ecological conditions that have decreased survival and natural reproduction. In January 2006, the Convention on International Trade in Endangered Species (CITES) suspended the trading of all wild beluga sturgeon caviar from the Caspian Sea. A year later, CITES re-opened the trade of beluga sturgeon, despite much pressure from researchers. Opening and closing beluga sturgeon trade impacts the market and affects many parties, including fishers, consumers, and managers. After completing this case, students will have a better understanding of the complex process of managing shared natural resources, specifically dealing with beluga sturgeon populations in the Caspian Sea region. This case will also allow students to expand their critical thinking skills for decision making on a global, ecological issue while learning about a complicated problem involving many opinions, countries, and livelihoods.

     Beluga sturgeon is a species that has been fished in the Caspian Sea since the middle 1800s (Raspopov, 1993a). This species is prized for its caviar; a kilogram of beluga sturgeon roe (or eggs) can sell on the United States market for more than US$5000. Recently, this fishery has attracted much attention due to decreasing abundance, with catches plummeting in the 1920s and continuing to decline during the past 20 years (Exhibit 1). Loss of habitat, overfishing, natural factors, and pollution have all contributed to the decline of beluga sturgeon. After the dissolution of the Soviet Union in 1991, management became more challenging as fishing rights were divided. Enforcement weakened, leading to more overfishing, poaching, and illegal trade. This case explores the issues surrounding this complicated problem and the management strategies that have been created in an attempt to protect this species from extinction. The Case

         The beluga sturgeon moved slowly through the currents of the Caspian Sea. Her sleek body was covered in prehistoric-looking bony plates, and the water quickly flowed around her as she searched for her next meal. Like all sturgeon, she used the sensitive barbels around her mouth to detect small organisms on the bottom. She stirred the sediment with her snout and felt movement. Quickly, she protruded her vacuum-like mouth into the sediment to slurp up the small crustacean buried in the mud. Most of the time, she did not feed this way. At her large size, she usually swam through the middle of the water column feeding on larger fish. However, instinct told her that she had to take advantage of every available food source. Soon she would begin her spawning migration, a trek that would cover over a 1000 kilometers and would be accompanied by long periods of starvation.

The White sturgeon Fish

         White sturgeon (Asipenser transmontanus) within the Nechako watershed have been intensively studied over the past 20 years (Aitken 1981; Dixon 1986; Envirocon 1982,1983,1984; RL&L1995- 1999). The current condition of the sturgeon population is now fairly well understood, but as the historic distribution and population levels are unknown, the state of the relative health of the species is not clear. Prior to the last 20 years, although the sturgeon have been fished continuously, little if any study on the Nechako resident species has been conducted. What was known of the sturgeon in the region was local knowledge, held by a few interested parties. At one time in the early 1900s, an attempt was made by the then fisheries commission to record the fishing statistics of the sturgeon in the Nechako and Stuart Rivers, but this attempt failed, due to the lack of participation of most of the fishers.

         Recent studies have attempted to increase the knowledge base about this little documented fish, and in doing so, a concern has been raised regarding the future of the Nechako white sturgeon. The concern has been strong enough for the fish to be placed on the “vulnerable” list by the federal Committee on the Status of Endangered Wildlife in Canada in 1991. The term “vulnerable” refers to species ‘subject to change in response to fishing pressure and habitat disturbance’ (Echols 1995). In 1995 the BC government downgraded the sturgeon’s status to ‘endangered’. Small catch numbers, and evident low numbers of juveniles in the population have sparked this concern. This project has been conducted in an effort to provide information by which the validity of these concerns may be determined. The intent was to gather information regarding the population as it was prior to changes in the hydrology of the system (impacts caused directly and indirectly by the construction of the Kenney Dam), and the increase of sturgeon fishing generated by the influx of people into the community in the early 1900s and later, in the 1960s and 1970s.

       The study was designed to examine the historic distribution of the White Sturgeon in the Nechako Watershed. A document review and community interview process formed the basis of data collection. A second phase of the project is expected to be undertaken in the spring that will include the participation of First Nations groups that utilize the watershed. Due to the short period of time allowed for this phase of the project, the main channel of the Nechako River was the focus, although references to the species in the Stuart River system were noted and included in the report. The goal of this project was to gather, organize, and summarize information. It is expected that this information will serve to assist in the development of a sturgeon recovery program in the Nechako River drainage by the Ministry of Environment, Lands and Parks. A chronological reference list is attached as an appendix to this report.

The Goby fish

             The first sighting of a round goby in the United States was in the St. Clair River in 1990. They most likely arrived through the ballast water of freighter vessels. The round goby found its way into Lake Erie and Lake Michigan by 1993. In only a year, these populations became established. By 1995, round gobies were found in Lake Superior and other parts of Lake Erie and Lake Michigan. Due to the disjunctive populations found in the early years, it is likely that these populations represented different introductions. One population in Lake Michigan was found 12 miles east of the Grand Calumet River. This river is connected to the Mississippi River meaning that there is the potential for the gobies to spread into America’s largest watershed.

        

         Round gobies likely hitchhiked in the ballast water from ships coming from the Black and Caspian Seas. Once in the Great Lakes, they were able to establish a dense population very rapidly. Just as with their initial introduction pathway, round gobies could be picked up in ballast water from the Great Lakes and taken to other locations in the United States. Most at risk is the Mississippi River due to the Chicago Sanitary and Ship Canal that links the Great Lakes vessels with the Illinois River (Mississippi River drainage). Round gobies have already spread to one Indiana inland lake, Wolf Lake. There is a waterway connection between Lake Michigan and Wolf Lake that allowed the gobies to swim into the inland lake. The round goby can also swim into the Mississippi River drainage through the Chicago Sanitary and Ship Canal. An electric dispersal barrier has been installed in the canal to prevent fish migration between the two watersheds. At this time, no gobies have made their way into the Mississippi basin. Anglers and aquarium hobbyists are also a possible mode of dispersing this species to other bodies of water. However, it is illegal to possess a live round goby in Indiana. If a goby is caught, it must be killed immediately and not returned alive.