Aquaculture Impacts Research Papers

This guidebook is written to help local governments and the communities whom they govern, address the negative environmental impacts associated with aquaculture. Fish kills, red tide, eutrophication, and other forms of aquatic pollution... more

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- by Patrick White
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- 2
  Aquaculture Impacts, Aquaculture Management

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- by Patrick White
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- Aquaculture Impacts

The exploitation of Atlantic salmon, Salmo salar, in food and recreational fisheries has a long history in the rivers and coastal waters of the species range. Fortunately, prior to the last few centuries, when river stocks were largely... more

The well being of fish populations is directly affected by a number of interconnected environmental parameters such as dissolved oxygen, temperature, eutrophication of the water column that affects the qualitative and quantitative... more

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- by Patrick White
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- 2
  Marine Aquaculture, Aquaculture Impacts

Study on length weight relationship and condition factor of whiteleg shrimp Litopenaeus vannamei (Boone, 1931) cultured in earthen pond, Khambhat (Gujarat) SD Prajapati and NC Ujjania Abstract The length-weight relationship and condition... more

The project TCP/RAS/3203 "Reducing the dependence on the utilization of trash fish/ low-value fish as an aquaculture feed for marine finfish in the Asian region" involved assessing and comparing the environmental impacts between fish fed... more

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- by Patrick White
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- Aquaculture Impacts

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- by Patrick White and +1
  Teresa Fernandes
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- Aquaculture Impacts

Exotic salmonids were deliberately introduced to the Southern Hemisphere during the last part of the 20th century, initially to boost sport fishing and later to develop an aquaculture industry. Early introductions were justified by... more

Exotic salmonids were deliberately introduced to the Southern Hemisphere during the last part of the 20th century, initially to boost sport fishing and later to develop an aquaculture industry. Early introductions were justified by governments on purely utilitarian arguments as it was felt that translocated salmonids would capitalize on otherwise 'underutilized' aquatic niches. A century later, exotic salmonids are established in nearly all places where they were originally introduced and beyond, and constitute one of the main threats to endemic fish fauna, amongst which galaxiid fishes have perhaps been impacted the most. We screened the literature to document the changing perspectives on exotic salmonids in the Southern Hemisphere, and employed SWOT analysis to assess the conservation prognosis of native galaxiids in the face of salmonid invasions. Our analysis indicates that opinions differ - and contradictions abound - as to how to prevent further salmonid encroachment. This is largely due to lack of information on the impact of exotics but, more importantly, because the problem is often approached merely from a socio-economic perspective. Sport fishermen, for example, actively support the stocking of rivers to enhance sport fisheries and argue in favour of considering established salmonids as part of the native biodiversity, but also want to see an end to salmonids escaping from fish farms. The salmon industry tends to stress the social and economic benefits brought about by aquaculture, but continues to demand the right to expand and self-regulate. Governments, on the other hand, have not always had consistent or clear policies on exotic salmonids, and have tended to favour some stakeholders and penalized others. Our analysis emphasizes the need to consider biologically meaningful time scales when assessing impacts on biodiversity, and stresses the need to anticipate shifts in public opinion and stakeholder support in conservation. Key words: aquaculture, conservation, Convention on Biological Diversity, galaxiids, impacts, invasive species, salmonids, sport fishing, stocking, SWOT.

From 1983 to 1986 the Rivers Asón and Nansa (northern Spain) were stocked with over 100 000 eyed ova year-1 from a Scottish hatchery in an effort to increase angling catches of Atlantic salmon. An inherent genetic marker was used to... more

This paper is written to present the current situation of the Philippine aquaculture industry, focusing on the impacts of feed wastage and inappropriate feeding to the environment, as well as its effects to the operators economically in... more

In Chilean Patagonia relatively pristine aquatic environments are being modified by the introduction of exotic salmonids, initially through their deliberate release for sport fishing since the early 20th century, and more recently via the... more

This paper examines two areas to be considered in developing conservation plans for Atlantic salmon (Salmo salar): goal statements and the general framework for the implementation of a conservation plan. From a biological perspective, the... more

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- by Julian Dodson
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- 10
  Zoology, Fisheries, Conservation Ecology, Ecology

Aplochiton zebra (peladilla, zebra trout) is a galaxiid fish endemic to Patagonia and the Falkland Islands, where populations are threatened by salmonid introductions. Here we describe the isolation and characterization of 13 polymorphic... more

Aquaculture is a major source of invasive aquatic species, despite the fact that cultured organisms often have low genetic diversity and tend to be maladapted to survive in the wild. Yet, to what extent aquaculture escapees become... more

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- by Carlos Garcia de Leaniz
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- 8
  Conservation Ecology, Invasive Species, Chile, Salmonids

A previous analysis of proportions of stocked and wild Atlantic salmon among angled fish in the Rivers Ason and Nansa in northern Spain based on the analysis of MEP-2* genotypes is extended. The results reinforce the initial conclusion... more

The length-weight relationship and condition factor of whiteleg shrimp Litopenaeus vannamei were described in present paper. For proposed research work the length and weight of the shrimp was measured from earthen pond of Moriraj Aqua... more

Here we critically review the scale and extent of adaptive genetic variation in Atlantic salmon (Salmo salar L.), an important model system in evolutionary and conservation biology that provides fundamental insights into population... more

This paper examines two areas to be considered in developing conservation plans for Atlantic salmon (Salmo salar): goal statements and the general framework for the implementation of a conservation plan. From a biological perspective, the... more

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- by Jennifer L Nielsen
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- 10
  Zoology, Fisheries, Conservation Ecology, Ecology

Exotic fishes are a principal threat to global freshwater biodiversity. Rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta are the world's two most widespread exotic fishes, dominate the fish communities of most cold-temperate... more

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- by Carlos Garcia de Leaniz
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- 7
  Conservation Ecology, Invasive Species, Chile, Salmonids

Exotic salmonids were deliberately introduced to the southern hemisphere during the last part of the 20th century, initially to boost sport fishing and later to develop an aquaculture industry. Early introductions were justified by... more

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- by Gonzalo Gajardo
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- 25
  Socioeconomics, Public Opinion, Conservation, Stakeholders

We used an invaded stream fish community in southern Chile to experimentally test whether the diversity of exotic species affects their competitive impact on a native species. In artificial enclosures an established invasive, rainbow... more

Here we critically review the scale and extent of adaptive genetic variation in Atlantic salmon (Salmo salar L.), an important model system in evolutionary and conservation biology that provides fundamental insights into population... more

Here we critically review the scale and extent of adaptive genetic variation in Atlantic salmon (Salmo salar L.), an important model system in evolutionary and conservation biology that provides fundamental insights into population persistence, adaptive response and the effects of anthropogenic change. We consider the process of adaptation as the end product of natural selection, one that can best be viewed as the degree of matching between phenotype and environment. We recognise three potential sources of adaptive variation: heritable variation in phenotypic traits related to fitness, variation at the molecular level in genes influenced by selection, and variation in the way genes interact with the environment to produce phenotypes of varying plasticity. Of all phenotypic traits examined, variation in body size (or in correlated characters such as growth rates, age of seaward migration or age at sexual maturity) generally shows the highest heritability, as well as a strong effect on fitness. Thus, body size in Atlantic salmon tends to be positively correlated with freshwater and marine survival, as well as with fecundity, egg size, reproductive success, and offspring survival. By contrast, the fitness implications of variation in behavioural traits such as aggression, sheltering behaviour, or timing of migration are largely unkown. The adaptive significance of molecular variation in salmonids is also scant and largely circumstantial, despite extensive molecular screening on these species. Adaptive variation can result in local adaptations (LA) when, among other necessary conditions, populations live in patchy environments, exchange few or no migrants, and are subjected to differential selective pressures. Evidence for LA in Atlantic salmon is indirect and comes mostly from ecological correlates in fitness-related traits, the failure of many translocations, the poor performance of domesticated stocks, results of a few common-garden experiments (where different populations were raised in a common environment in an attempt to dissociate heritable from environmentally induced phenotypic variation), and the pattern of inherited resistance to some parasites and diseases. Genotype Â environment interactions occurr for many fitness traits, suggesting that LA might be important. However, the scale and extent of adaptive variation remains poorly understood and probably varies, depending on habitat heterogeneity, environmental stability and the relative roles of selection and drift. As maladaptation often results from phenotype-environment mismatch, we argue that acting as if populations are not locally adapted carries a much greater risk of mismanagement than acting under the assumption for local adaptations when there are none. As such, an evolutionary approach to salmon conservation is required, aimed at maintaining the conditions necessary for natural selection to operate most efficiently and unhindered. This may require minimising alterations to native genotypes and habitats to which populations have likely become adapted, but also allowing for population size to reach or extend beyond carrying capacity to encourage competition and other sources of natural mortality.

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- by Dmitry Lajus and +1
  Asbjørn Vøllestad
- •
- 24
  Conservation Biology, Conservation Genetics, Population Genetics, Reproduction

Over the last 50 years, Spanish Atlantic salmon (Salmo salar) populations have been in decline. In order to bolster these populations, rivers were stocked with fish of northern European origin during the period 1974-1996, probably also... more

Here we critically review the scale and extent of adaptive genetic variation in Atlantic salmon (Salmo salar L.), an important model system in evolutionary and conservation biology that provides fundamental insights into population... more

This paper examines two areas to be considered in developing conservation plans for Atlantic salmon (Salmo salar): goal statements and the general framework for the implementation of a conservation plan. From a biological perspective, the... more

The tendency of salmon, Salmo salar, to return from the sea to the river of hatching and form 'local populations' has apparently been known for a long time (Calderwood 1908). Writing in 1653, Izaak Walton described how juveniles marked... more

We used an invaded stream fish community in southern Chile to experimentally test whether the diversity of exotic species affects their competitive impact on a native species. In artificial enclosures an established invasive, rainbow... more

Rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta are the world's two most widespread exotic fishes, dominate the fish communities of most coldtemperate waters in the southern hemisphere and are implicated in the decline and... more

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- by Gonzalo Gajardo
- •
- 11
  Conservation Ecology, Invasive Species, Chile, Salmonids

We used an invaded stream fish community in southern Chile to experimentally test whether the diversity of exotic species affects their competitive impact on a native species. In artificial enclosures an established invasive, rainbow... more

Electrophoretic studies of proteins remain a primary source of insight into genetic diversity in many species including the Atlantic salmon Salmo salar, one of the most culturally and economically important fish species of the North... more

Electrophoretic studies of proteins remain a primary source of insight into genetic diversity in many species including the Atlantic salmon Salmo salar, one of the most culturally and economically important fish species of the North Atlantic region. Since 1966, >350 scientific papers on protein variation have been published encompassing 25 000þ salmon from over 400 locations in >200 river systems across the species' distribution. Variation has been detected at 30% of the 110 protein loci screened, though most studies examine <40. The method has been applied largely to the investigation of population structure and differentiation, but work has also led to the systematic revision of the genus Salmo and remains the primary source of insight into hybridization in the wild with brown trout Salmo trutta. Spatial patterns of differentiation show temporal stability, both within and among river systems, and strongly support structuring of the species into river and tributary specific populations and the designation of European and North American populations as distinct sub-species. They also show widespread regional differentiation within both continents, beyond the marked subcontinental differences between Baltic Sea and Atlantic Ocean populations in Europe. Most of the differentiation probably reflects gene flow and founder events associated with colonization following the retreat of the glaciers from much of the species' modern range. However, variation at MEP-2* shows strong correlations with environmental temperature, both within and among rivers, and associations with phenotypic performance. This suggests selection is acting on the locus and provides †Author to whom correspondence should be addressed. Tel.: þ44 (0) 796 472060; fax: þ44 (0) 1796 473523; # 2005 Crown copyright compelling evidence for the local adaptation of populations. Protein studies have led to more population centred management of the species and have been exploited in the discrimination of regional stocks in mixed stock analysis in high seas fisheries, particularly in the Baltic Sea, and as markers for the assessment of stocking success. They have also advanced insight into how the genetic character of populations can be changed in cultivation and the potential impact of salmon aquaculture and stocking on wild populations. The method has been largely superseded by DNA based analyses, but the results remain highly relevant to Atlantic salmon management and conservation and are an irreplaceable data set for studying genetic stability of populations over time. # 2005 Crown copyright

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- by Kjetil Hindar
- •
- 13
  Genetics, Zoology, Population Genetics, Conservation Ecology

Electrophoretic studies of proteins remain a primary source of insight into genetic diversity in many species including the Atlantic salmon Salmo salar, one of the most culturally and economically important fish species of the North... more

Electrophoretic studies of proteins remain a primary source of insight into genetic diversity in many species including the Atlantic salmon Salmo salar, one of the most culturally and economically important fish species of the North Atlantic region. Since 1966, >350 scientific papers on protein variation have been published encompassing 25 000+ salmon from over 400 locations in >200 river systems across the species' distribution. Variation has been detected at 30% of the 110 protein loci screened, though most studies examine <40. The method has been applied largely to the investigation of population structure and differentiation, but work has also led to the systematic revision of the genus Salmo and remains the primary source of insight into hybridization in the wild with brown trout Salmo trutta. Spatial patterns of differentiation show temporal stability, both within and among river systems, and strongly support structuring of the species into river and tributary specific populations and the designation of European and North American populations as distinct sub-species. They also show widespread regional differentiation within both continents, beyond the marked subcontinental differences between Baltic Sea and Atlantic Ocean populations in Europe. Most of the differentiation probably reflects gene flow and founder events associated with colonization following the retreat of the glaciers from much of the species' modern range. However, variation at MEP-2* shows strong correlations with environmental temperature, both within and among rivers, and associations with phenotypic performance. This suggests selection is acting on the locus and provides compelling evidence for the local adaptation of populations. Protein studies have led to more population centred management of the species and have been exploited in the discrimination of regional stocks in mixed stock analysis in high seas fisheries, particularly in the Baltic Sea, and as markers for the assessment of stocking success. They have also advanced insight into how the genetic character of populations can be changed in cultivation and the potential impact of salmon aquaculture and stocking on wild populations. The method has been largely superseded by DNA based analyses, but the results remain highly relevant to Atlantic salmon management and conservation and are an irreplaceable data set for studying genetic stability of populations over time

Aquaculture Impacts

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