Quantitative genetics and management of wild populations

Quantitative genetics and management of wild populations

102 Selected abstracts ish population and least developed by humans) and Colorado (far fewer fish and more development) rivers, and prospects for th...

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Selected abstracts

ish population and least developed by humans) and Colorado (far fewer fish and more development) rivers, and prospects for the future are reviewed. Timely and unimpeded flow of water through an extensive and diversified reach of river must be provided ff this top carnivore and its ecosystem are to be preserved. -from Editors 92Z/10563 Interactions between cultured and wild Atlantic salmon. Proceedings of a symposium, Loen, Norway, 23-26 April, 1990 ed L. P. Hansen & others, Aquaculture, 98(I-3), 1991, pp 1-324. Farming of Salmo salar began in c1970. In 1989 the total production in the Noxth Atlantic was c170 000 t, with Norway producing 115 000 t and Scotland 30 000 t. Salmon escape from the net-pens. Concern has mainly focused on 1) the dilution or elimination of distinctive gene pools by the breaking down of isolation mechanisms between stocks, resulting in a possible reduction in fitness of the wild stocks due to the introduction of non-indigenous genes or gene combinations; and 2) transfer of disease from farmed to wild fish or vice versa. The 1990 symposium reported in these papers consisted of sesstons on migration and development of cultured salmon; salmon spawning behaviour;, ecological interference; genetic interaction; diseases and parasites; containment; and synthesis. -after Editor 92Z/10564 Potential interaction between cultured and wild Atlantic salmon R . L . Saunders, Aquaculture, 98(1-3), 1991, pp 51-60. Gives an overview of the potential interaction between cultared and wild Saline salar in respect to disease, parasites, behaviur-ecology and genetics. Diseases are a more serious threat to reared than to wild salmon owing to intensive culture, resulting stressful conditions and the ease of transmission of pathogens. Metazoan parasites can pose serious threats to both farmed and wild salmon. Sea lice are of little danger to wild salmon but are a major concern in salmon mariculture. The fluke Gyrodactylus salaris is a serious threat to wild salmon in Norway where the parasite has been recently introduced from the Baltic area. Behavioral and ecological interaction between cultured and wild salmon is likely since cultured salmon do enter rivers and spawn. The two forms do interbreed but the extent is unknown. Cultured salmon quickly become genetically dissimilar to the wild stocks from which they are derived. Wild stocks have developed unique genotypes which are adaptive to local conditions and life history imperatives. Reasonably precise homing behavior is responsible for development of unique genotypes and for helping to maintain this uniqueness. -from Author 92Z/10565 The t h r e a t of extinction to native populations experiencing spawning intrusions by cultured Atlantic salmon J . A . Hutchings, Aquaculture, 98(1-3), 1991, pp 119-132. The probability of interbreeding between cultured and native $almo salar depends on the existence of behavioural, developmental, and morphological reproductive isolating mechanisms and on the relative competitive abilities of cultured and native salmon. The author modelled the influence o f spawning intrusions on population size by varying the proportional representation o f cultured salmon in the spawning population, the frequency of spawning intrusions, and the difference in fitness between the two forms for three mating situations (no interbreeding and interbreeding with and without hybrid dysgenesis). The extinction probability of native genomes is greatest when interbreeding occurs between native salmon and relatively large numbers of frequently intruding cultured salmon. The threat of extinction is greatest for small populations, is influenced by genetic (interbreeding between forms) and non-genetic (increased density) factors, and is inextricably linked with the probability of co-occurrence of the two forms. -from Author 92Z/10566 Quantitative genetics a n d management of wild populations H . B . Bentsen, Aquaculture, 98(1-3), 1991, pp 263-266. Traditional strategies for management and preservation of

wild populations have focused on genetic properties that may b e characterized in terms of aIlelic variation. Studies on Norwegian strains o f Atlantic salmon Saline salar indicate that this theoretical framework may be too restricted to provide appropriate management strategies. The concepts of quantitative genetics should be applied as an additional source of information to improve the strategies. -Author 92Z/10567 Attempts to reduce the impact of r e a r e d Atlantic salmon on wild in Norway P . I . Bergan, D. Gansen & L. P. Hansen, Aquaculture, 98(1-3), 1991, pp 319-324. The most impor'cmt elements are rational location of fish farms, technical improvements at the farms, effective routines for catching escaped fish in the sea and in the rivers, strengthening of the wild salmon stocks by stock enhancement and strict regulations for salmon fishing. A gene bank for Saline salar stocks has been established to safeguard the genes of local wild salmon stocks for the future. -from Authors 92Z/10571 Aloft again T. Gallagher, Living Bird Quarterly, 10(4), 1991, pp 30-35. The conservation efforts undertaken during the 1980s to protect and manage the last population of California condots Gymnogyps californianus are outlined. The last wild bird was captured in 1987 and a captive breeding population established. Now in 1991 because of the success of the programme the recovery team in charge of the condor is planning to release two birds as part of a reintroduction plan to establish three wild populations. -R.Land 92Z/10573 Networking L. X. Payne, Living Bird Quarterly, 10(4), 10(4), pp 24-29. The Western Hemisphere Shorebird Reserve Network was set in 1985 with the aim of protecting shorebird, especially wader, habitat throughout North andneotropical America. This paper describes the achievements o f the organization in terms of reserve establishment, training a n d research and the many efforts being made to protect this wildlife resource. -R.Land 92Z/10576 Creation and m a n a g e m e n t of artificial nesting sites for wetland birds N. D. Burgess & G. J. M. Hirons, Journal of Environmental Management, 34(4), 1992, pp 285-295. Since 1963 about 270 islands and 40 rafts have been constrocted and managed in Britain by the Royal Society for the Protection of Birds, mainly at its wetland reserves. These structures are primarily aimed at providing secure breeding sites for terns, waders, gulls, wildfowl and divers, including nine species of particular conservation importance in tsritain. Bare shingle, or sparsely vegetated islands and rafts, attract the most breeding species in southern coastal locations (up to 20 species), including five species of conservation importance; sandwich tern Sterna sandvicensis, little tern Sterna albifrons, avocet Recurvirostra avoseua and, occasionally, Mediterranean gull Larus melaocephalus and roseate tern Sterna dougallii. Similar unvegetated or sparsely vegetated islands on the coast in the north, or inland in the N or S of Britain, support few breeding species. The composition of the bird assemblage breeding on well-vegetated islands and rafts in Britain (up to 20 spe.cies) is less influenced by geographical location, but species of conservation importance such as pochard Aytlm ferina are found mainly m the south, and common scoter Melanitta nigra, red-throated diver Gavia stellata and black-throated diver Gav/a arctica exclusively in Scotland. -from Authors 92Z/10578 Owl delivers message in forest management J. T. Olson & H. M. Anderson, Forum for Applied Research & Public Policy, 6(3), 1991, pp 24-28. Declared a threatened species in June 1990, the northern spotted owl Str/x occidentalis caurina could put as many as three million acres of national forests off limits to timber harvesters and deal a heavy blow to the regional economy