Fishing

About: Fishing is a research topic. Over the lifetime, 26543 publications have been published within this topic receiving 455552 citations. The topic is also known as: angling.

Warm, windy winters drive cod north and homing of spawners keeps them there

Abstract: Summary 1 Climatic and anthropogenic effects often interact leading to unexpected results. For example, climate may lead to a change in the spatial distribution of a fish stock and thereby its vulnerability to exploitation. The North Sea cod stock is currently under pressure from both environmental change and human exploitation. This stock has experienced a series of poor recruitments since the late 1990s and, concomitant with the decrease in abundance, the distribution of cod has changed. While it has been suggested that the change in distribution can be linked to increasing temperatures and fishing pressure, there is little evidence for this hypothesis. 2 Using winter and summer survey catches, we investigated whether a directional shift in the distribution of cod has taken place over the years 1983–2003. We then examined whether the change could be linked to climatic conditions, fishing mortality, stock size or limited directional movement of cod. Using the derived models, we investigated whether fishing has increased the sensitivity of the cod population to climate-induced distribution changes. 3 A series of winters characterized by high temperatures and southerly winds during the egg and larval phases of cod led to a northward shift in the distribution of juvenile North Sea cod the following year. A concomitant northern shift of mature fish around the time of spawning was linked directly to a tendency for northerly distributed juveniles to remain northerly throughout their life. This shift of the spawners further augmented that of the new recruits. 4 Although fishing mortality on a North Sea scale was not directly correlated with the displacement of any of the age groups, fishing has severely decreased the number of fish in older age groups. This increased the sensitivity of the distribution of the cod stock to climatic changes. 5 Synthesis and applications. The centre of gravity of North Sea cod has moved north as a result of the effect of a series of warm, windy winters on the distribution of recently settled cod. The shift was followed by a northwards shift in the distribution of older age groups. Unless a series of cold and calm years combined with a reduced mortality in the southern areas allows a southern spawning population to rebuild, the cod stock is unlikely to return to its previous area of distribution. Furthermore, protecting adult cod mainly in northern areas is unlikely to result in improved recruitment to the southern North Sea.

Herring: Expectations for a New Millennium

Abstract: Herring is marketed for both fodder and human consumption in Finland. For the human consumption market, herring exceeding 36 g weight is preferred, whereas the fodder herring can be of any size. The main demand of fodder is based on fur production, and the rapid changes of fur markets have had a large impact on the herring fishery. There are variations not only in the markets but also in biological factors. The growth rate of northern Baltic herring has declined substantially in recent years due primarily to changes in prey of herring. The key factors determining the prey resources are the changing hydrography in the Baltic Sea and competition with sprat. It is also possible that changes in the cod stock, modification of fishing gear, and changes in fishing effort may have influenced the mortality rates of herring. Changing biological and market conditions have resulted in significant unforeseen changes in the location, composition, and behavior of the herring fisheries. Fishing in recent years has been concentrated in the Bothnian Sea, and an increasing share has been taken by large trawlers. As the demand of herring for fodder declined the unreported rejection of catches (discarding) may have increased. In addition, because of increases in trawl size and increase in fishing effort in the most important fishing area, there has been an increase in the number of fish escaping through the mesh—but this may have resulted in a higher subsequent mortality rate of herring due to trawl injury. These factors have reduced the production capacity of herring for the human consumption market during the 1990s. In this review, we formulate the driving bioeconomic factors of Finnish herring fishery and demonstrate the magnitude of changes, which are largely unpredictable and uncontrollable by fisheries management.

A framework for adaptive gear and ecosystem‐based management in the artisanal coral reef fishery of Papua New Guinea

Abstract: 1. Artisanal fishing on coral reefs in Papua New Guinea is an important livelihood activity that is managed primarily at the level of local communities. Pockets of overexploitation exist and are expected to increase with plans for increased commercialization. 2. This paper provides a current assessment of the artisanal multi-species coral reef fishery by examining selectivity of the dominant gear, namely line fishing, spearguns, and gill nets. Each gear has its own strengths and weaknesses in terms of use and conservation of resources, with no clear problem gear. 3. The three gears utilize different resources but there was moderate overlap in the species caught, particularly between gill nets and line fishing and marginally between lines and spearguns. Gill nets have the disadvantage of being destructive to coral and the advantage of catching commercial species. Line fishing catches an intermediate number of species but mostly large-bodied and predatory species that could potentially reduce predation and the mean trophic level of the fishery. Spearguns catch the highest numbers of species, including many non-commercial and herbivorous fish and could reduce the diversity of fish and encourage algal growth. 4. This information could be used in combination with scientific monitoring and traditional ecological knowledge to develop an adaptive management framework that uses local restrictions on the various gears to restore or balance the fishery and ecosystem. Restrictions could be selectively imposed: on gill nets when coral cover is low, line fishing when large-bodied predators are depleted, and spearguns when biodiversity is reduced and algal abundance high.

Effects of Angling on Bluegill Populations: Management Implications

Abstract: Angling would affect a fish population if it increased the total mortality rate, reduced numbers or biomass, or reduced the average size of fish in a population by removing the larger ones. Data from the literature indicate that angling commonly affects populations of bluegills Lepomis macrochirus. Substantial exploitation rates (mean, 27%) are not unusual; exploitation is directly related to fishing effort, and angling reduces average size and increases total mortality. Many exploited bluegill populations comprise mainly small fish, less than 150 mm long. Consistent high recruitment of young of the year, size-selective exploitation, and reduced growth and increased natural mortality from competition would tend to produce and maintain such a population size structure. Because angling affects populations, management steps to reduce angling mortality of larger fish, as well as to reduce density of small fish, seem desirable.

An assessment of seabird–fishery interactions in the Atlantic Ocean

Abstract: Currently, 17 of 22 albatross species are listed as Vulnerable, Endangered, or Critically endangered by the International Union for the Conservation of Nature (IUCN). Incidental mortality in fisheries is by far the most widespread cause of the population declines observed for these and other closely related species. In 2006, the International Commission for the Conservation of Atlantic Tunas (ICCAT) requested an assessment of the threat from their fisheries to all seabirds that breed or forage within their jurisdiction. Methods were developed to assess the potential consequences of fishing for more than 60 populations of seabird. The assessment framework involved the identification of at-risk populations, overlap analyses, estimation of total bycatch, and an evaluation of the impact of the bycatch on key selected populations for which there were sufficient data on bird distribution and demography. These were the wandering and black-browed albatrosses of South Georgia and the Atlantic yellow-nosed and Tristan albatrosses of Gough Island. Summary results from the seabird assessment are presented, revealing that ICCAT longline fisheries catch substantial numbers of seabirds, with potentially significant conservation implications. If this mortality is not reduced, the numbers of breeding birds in some populations will continue to decline, threatening their long-term viability.