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Commercial Fishing (commercial + fishing)

Distribution by Scientific Domains

Life Sciences	46%
Earth and Environmental Science	30%

Selected Abstracts

Body size-dependent responses of a marine fish assemblage to climate change and fishing over a century-long scale

GLOBAL CHANGE BIOLOGY, Issue 2 2010
MARTIN J. GENNER
Abstract Commercial fishing and climate change have influenced the composition of marine fish assemblages worldwide, but we require a better understanding of their relative influence on long-term changes in species abundance and body-size distributions. In this study, we investigated long-term (1911,2007) variability within a demersal fish assemblage in the western English Channel. The region has been subject to commercial fisheries throughout most of the past century, and has undergone interannual changes in sea temperature of over 2.0 °C. We focussed on a core 30 species that comprised 99% of total individuals sampled in the assemblage. Analyses showed that temporal trends in the abundance of smaller multispecies size classes followed thermal regime changes, but that there were persistent declines in abundance of larger size classes. Consistent with these results, larger-growing individual species had the greatest declines in body size, and the most constant declines in abundance, while abundance changes of smaller-growing species were more closely linked to preceding sea temperatures. Together these analyses are suggestive of dichotomous size-dependent responses of species to long-term climate change and commercial fishing over a century scale. Small species had rapid responses to the prevailing thermal environment, suggesting their life history traits predisposed populations to respond quickly to changing climates. Larger species declined in abundance and size, reflecting expectations from sustained size-selective overharvesting. These results demonstrate the importance of considering species traits when developing indicators of human and climatic impacts on marine fauna. [source]

Ecological research for development

AFRICAN JOURNAL OF ECOLOGY, Issue 2004
F. I. B. Kayanja
Abstract Uganda is rich in aquatic ecosystems. Commercial fishing involves an off-take that may not be ultimately sustainable. Aquatic ecosystems, like the forests, are under pressure. Forests, for many years to come, will remain the main source of energy for the people. They also continue to be cleared to make way for agricultural use of the land. Research for development must address problems of this kind as they are at the heart of the development process. [source]

Rhodolith bed diversity in the Gulf of California: the importance of rhodolith structure and consequences of disturbance

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue S1 2003
D.L. Steller
Abstract 1.Rhodolith beds, unattached coralline reefs, support a high diversity and abundance of marine species from both hard and soft benthos. We used surveys in multiple shallow (3,20 m) beds in the Gulf of California to (1) examine seasonal patterns in associated floral and faunal diversity and abundance, (2) compare differences in faunal associations between rhodolith beds and adjacent sedimentary habitats, (3) examine the importance of complexity of rhodolith structure to community structure, and (4) estimate the impact of anthropogenic disturbance on rhodoliths and associated species. 2.Macroalgal richness was seasonal, and beds supported higher richness in winter (to 36 species) than summer (6,7 species), primarily due to foliose red algae. Strong seasonal variation in the abundance of dominant cover organisms was due to a shift from macroalgae and mat-forming colonial invertebrate species to microalgae. 3.The community in a rhodolith bed of high-density thalli (El Coyote average ,11000 thalli/ m,2) had higher richness (52 versus 30 species) and abundance of epibenthic and crypto- and in-faunal species compared with an adjacent sand community. Species diversity and abundance was particularly high for unique cryptofaunal organisms associated with rhodolith interstices. Cryptofauna reached average densities of 14.4 organisms/ cm,3 rhodolith, the majority of which were crustaceans, polychaetes and cnidarians along with rhodolith-specific chitons. 4.Results from sampling across a range of rhodolith morphs in the El Requeson bed (with lower average cryptofaunal densities of 2.3 organisms/ cm,3) revealed that the total organisms supported by a rhodolith significantly increased with both complexity (branching density) and space available (thallus volume). These data suggest that reducing the population size structure, structural complexity and cover of living rhodoliths could decrease species richness and abundance. 5.While disturbance is a natural feature of these free-living beds, increased anthropogenic disturbance from trawling, anchoring and changes in water quality can directly impact the bed community through substrate alteration. Commercial fishing threatens rhodolith beds in the Gulf of California by decreasing rhodolith size and increasing sedimentation and burial rates. In addition to reducing direct destruction, conservation efforts should also focus on decreasing practices that breakdown thalli. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Nodularin uptake by seafood during a cyanobacterial bloom

ENVIRONMENTAL TOXICOLOGY, Issue 6 2001
P. G. Van Buynder
Abstract The problem of blue-green algal toxin contamination of recreational waters and drinking water catchments is well described, as is the potential contamination of associated seafood. Algal contamination of Victorian waterways is now a widespread annual occurrence and, in some regions, the intersection of blooms and commercial fishing threatens the food safety of large numbers of people. Toxin levels which produce no observed adverse effect in animal studies were used to derive safe tolerable daily intake levels. These ,acceptable levels' were then modified to protect against potential acute health risks associated with short-term exposures. National food surveys were used to derive likely seafood intakes and thus, in combination with ,safe toxin levels', health alert levels for seafood were formulated. During the summer of 2001 a bloom of Nodularia spumigena occurred in the Gippsland Lakes area of Southern Victoria. During the bloom, seafood samples were collected and nodularin concentrations were estimated. Nodularin concentrations reached levels of concern in mussels and in prawn viscera at cell counts as low as 30,000 cells/ml. Nodularin concentrations in the flesh of finfish remained low. Boiling the seafood redistributed toxin between viscera and flesh. The results were used to restrict some seafood harvesting. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 468,471, 2001 [source]

Managing non-target, data-poor species using catch limits: lessons from the Alaskan groundfish fishery

FISHERIES MANAGEMENT & ECOLOGY, Issue 4 2010
R. F. REUTER
Abstract, The 2006 reauthorisation of the Magnuson-Stevens Fishery Conservation and Management Act requires annual catch limits for all target and non-target species within federally managed fisheries in the United States. In Alaska, both target and non-target species in the Alaska groundfish fisheries have been managed using catch limits since the early 1990s. Non-target species that are caught incidentally in a fishery require monitoring to ensure that the population is not negatively impacted by commercial fishing. Resource assessment scientists have been challenged with obtaining sufficient data to recommend an acceptable catch level for management of these species. This paper reviews three case studies where a catch limit is determined for non-target species when certain data are limited: (1) varying levels of biomass and catch data for all species within a species group or complex; (2) adequate catch data but no biomass data; (3) emerging target fishery of data-poor species, plus an example of how a complex of ecosystem component species is managed. [source]

The development of the Finnish inland fisheries system

FISHERIES MANAGEMENT & ECOLOGY, Issue 4-5 2001
M. Sipponen
The efficiency of Finnish inland fisheries administration has improved during the past 15 years because of changes in fisheries legislation. The establishment of regional management units particularly has improved the practice of co-management, which has allowed the participation of many relevant interest groups in the decision-making process. The long-term private market equilibrium supply for recreational fishing with active types of gear accounted for 50% of the Finnish lake surface area. Presently the public sector has become involved in the supply of recreational fishing licences. The improvement in the system owes much to political initiatives. As regards commercial fishing, state-ownership of fishing grounds is a channel for recruitment into the occupation. Private ownership has led to a suboptimal allocation of fisheries resources, particularly in the commercial branch of the industry. However, by giving priority to social instead of economic goals the statutory fishery associations will help to maintain social and community values, which are locally important. [source]

Body size-dependent responses of a marine fish assemblage to climate change and fishing over a century-long scale

Annual trend of fish assemblages associated with FADs in the southern Tyrrhenian Sea

JOURNAL OF APPLIED ICHTHYOLOGY, Issue 3 2007
F. Andaloro
Summary A study on fish assemblage associated with fish aggregating devices (FADs) in Sicily was carried out between January 2000 and January 2001. With a fortnightly periodicity, 156 experimental hauls were carried out by means of a purse seine in a FAD-containing marine section banned to commercial fishing. A total of 14 229 fish specimens belonging to six families and 10 species was found. These species were Balistes carolinensis, Caranx crysos, Naucrates ductor, Seriola dumerili, Seriola fasciata, Tachurus picturatus, Coryphaena hippurus, Schedophilus ovalis, Thunnus thynnus, Polyprion americanus and showed all young-of-the-year undergoing a rapid growth. The applied ordination technique highlighted the existence of four assemblage periods describing the annual trend. The results confirm that fish assemblages associated with FADs are related to season, following a fish colonization tied to natural recruitment. Comparison of the ecological indices across the four periods showed that the assemblages in the periods from summer to winter were more structured than those in spring. The quantity of individuals also showed a strong variation peaking in the summer period. The results of this study reveal that FADs represent a particular nursery area for the associated species that could influence their survival. [source]

FISH, FISHERS, SEALS AND TOURISTS: ECONOMIC CONSEQUENCES OF CREATING A MARINE RESERVE IN A MULTI-SPECIES, MULTI-ACTIVITY CONTEXT

NATURAL RESOURCE MODELING, Issue 4 2002
JEAN BONCOEUR
ABSTRACT. This paper investigates some economic consequences of creating a marine reserve on both fishing and ecotourism, when the range of controllability of fishing effort is limited and the impact of the reserve on ecosystem is considered. The issue is illustrated by the example of creating a no-take zone in part of a region where fishing is managed through a limited entry license system, and which is inhabited by two interacting stocks: a stock of prey (fish) and a stock of predators (seals). While the former is targeted by commercial fishing, the latter is not subject to harvest but is a potential basis for a commercial non-extractive activity (seal watching). Analysis is conducted with the help of a bioeconomic model combining the features of marine reserve modeling and of multispecies modeling. Following a description of the model, results of several simulation runs are presented. These show that creating a marine reserve has more complex economic implications than predicted in studies focused exclusively on one stock and/or commercial fisheries. More specifically, the model shows that the dynamics of the two interacting stocks reduces the benefits of the no-take zone for the fishing industry, while it makes the creation of this zone provide an opportunity for the development of ecotourism. Due to this dynamics, the model suggests that the optimal size of the reserve is larger when ecotourism is taken into account along with fishing activities. [source]

Ergonomic exposure case studies in Massachusetts fishing vessels

AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue S2 2002
Scott Fulmer MS
Abstract Background Musculoskeletal disorders may not have been studied as much as greater risks in the dangerous environment of commercial fishing. Primary prevention of risk for these kinds of injuries and illnesses begins by a detailed understanding of what risks are likely to be common in the different fisheries, and how those risks might be reduced. Methods Ergonomic job analyses were conducted on three different types of fishing vessels in Massachusetts: gillnetting, otter trawling, and lobstering. Direct observation was used to link posture to task. Noise measurements, tool analysis, and cycle time measurements were also included. Results Production speed, materials handling, and vessel movement contributed to musculoskeletal stress by affecting observable postural deviation, repetition, and forceful exertions. Conclusions Interventions to reduce ergonomic risk factors might be possible through utilization of below deck space in certain boats, through better technology, or through simple tool adjustments. Am. J. Ind. Med. Suppl. 2:10,18, 2002. © 2002 Wiley-Liss, Inc. [source]

Taxonomic confusion and market mislabelling of threatened skates: important consequences for their conservation status

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 3 2010
Samuel P. Iglésias
Abstract 1.The iconic European common skate (Dipturus batis) has been described as the first clear case of a fish species brought to the brink of extinction by commercial fishing. Its listing was upgraded to Critically Endangered on the 2006 IUCN Red List of Threatened Species. According to FAO fishery statistics, France is responsible for 60.2% of the 502 tonnes reported as ,D. batis' in the 2005 world landings. 2.Noticeable phenotypic differences within the species and inconsistencies in published data on its sexual maturation required careful re-examination of its taxonomy. Morphology, genetics, and life history reveal that two distinct species have been erroneously confused since the 1920s under the single scientific name D. batis. Here it is argued that they should be resurrected as two valid species. The common skate D. batis species-complex is split into two nominal species, the blue skate (provisionally called D. cf. flossada) and the flapper skate (D. cf. intermedia) with maximum lengths of 143.2,cm and 228.8,cm respectively. 3.This taxonomic confusion puts into question all previously accumulated data based on D. batis. Its endangered status highlights the need for an extensive reassessment of population collapses with accurately identified species. In 2006/2007 an extensive survey (4110 skates, 14.081 tonnes by weight) was conducted in the main French ports of the D. batis species-complex and relatives (D. oxyrinchus, D. nidarosiensis and Rostroraja alba) that are mixed together in landings under the names ,D. batis' and ,D. oxyrinchus'. 4.The survey reveals that official fishery statistics mask species-specific declines, due to the mislabelling of five species under only two landing names. Trends in landings since the 1960s and the life history of these species suggest a dramatic decline and collapse of the spawning stock, preventing the recovery of relict populations. 5.The risk of extinction of these depleted species may be higher than previously assessed and might be unavoidable without immediate and incisive conservation action. Copyright © 2009 John Wiley & Sons, Ltd. [source]

EXPLOITING MARINE WILDLIFE IN QUEENSLAND: THE COMMERCIAL DUGONG AND MARINE TURTLE FISHERIES, 1847,1969

AUSTRALIAN ECONOMIC HISTORY REVIEW, Issue 3 2008
Ben Daley
commercial fisheries; dugongs; Great Barrier Reef; marine turtles; Australia The historical exploitation of marine resources in Queensland has only been partially documented. In particular, the history of the commercial fishing of dugongs and marine turtles has received comparatively little scholarly attention. Since European settlement in Queensland, various human activities have exploited these resources. We present documentary and oral history evidence of the scale of those industries. Based on extensive archival and oral history research, we argue that diverse fishing practices occurred and that the sustained exploitation of dugongs, green turtles, and hawksbill turtles led to observable declines in the numbers of these animals , now species of conservation concern. [source]

Optimal management of the New Zealand longfin eel (Anguilla dieffenbachii),

AUSTRALIAN JOURNAL OF AGRICULTURAL & RESOURCE ECONOMICS, Issue 4 2005
Graeme J. Doole
Annual recruitment of the New Zealand longfin eel (Anguilla dieffenbachii) has decreased by 75 per cent since significant levels of commercial fishing began in the early 1970s. This motivates application of a multiple-cohort bioeconomic model to a New Zealand longfin eel fishery to investigate its optimal management and ascertain the suitability of existing regulatory policy. The use of historical harvest to calculate total allowable catch is asserted to be unsustainable based on recovery dynamics. In addition, individual transferable quota systems are argued to be fundamentally flawed for the protection of longfin fisheries because of high-grading, low-surplus production and a current lack of effective stock-assessment procedures. Area closure and the spatial definition of harvest rights are attractive alternatives given the territoriality of longfins and high larval spillover. The importance of unfished reserves is reinforced when significant uncertainties regarding population strength, harvest intensity and growth dynamics are considered. Restriction of exploitation to older cohorts in fished areas is demonstrated to maximise economic yield. [source]