Search results for "fishing"
showing 10 items of 172 documents
La remontée du saumon pour le frai dans le fleuve Tornionjoki, suivie au moyen d'un sonar à double faisceau horizontal.
2000
Fixed location split-beam horizontal echosounding was used to assess the size and timing of the Atlantic salmon (Salmo salar) spawning run in the River Tornionjoki. Four transducers, two on each river bank, were mounted across the river at the study site 4 km upstream from the river mouth. Net weirs were used on both shores to direct the passage of fish through the acoustic beams. Hydroacoustic monitoring covered 40-50% of the river cross-sectional area. Also test fishing and yearly catch statistics of salmon were used as an indication of the size of the spawning run in the river. Altogether, 7 700, 5 300 and 4 300 salmon-sized targets (target strength, TS ≥ -29 dB) moving upstream were det…
Demographic effects of full vs. partial protection from harvesting: inference from an empirical before-after control-impact study on Atlantic cod
2015
Summary In recent years, marine protected areas (MPAs) excluding all or some fishing activities have become widely applied as a tool to rebuild marine ecosystems and fisheries, but still, our knowledge of the effects of MPAs on the demography of harvested populations remains scarce, especially in cases where partly protected areas are still supporting some fishing activities. Here, we investigated the influence of partial protection – excluding fixed gears such as gillnets and traps but still allowing a hook and line fishery – on the demography of Atlantic cod Gadus morhua along the Norwegian Skagerrak coast. To do so, we applied novel multi-event models to a 9-year data set containing both…
Artificial Reefs in the Gulf of Castellammare (North-West Sicily): A Case Study
2000
Most of the plans for fish stock replenishment recently undertaken in Sicily have focused on the Gulf of Castellammare. Reasons for choosing this biotope for a restocking plan include the size of the Gulf (300 km2), the importance and traditional role of its fisheries and the existence of information describing the local marine environment. The Gulf of Castellammare is the widest bay in Sicily and fishing has always played a major role in the local economy. Today income from fishing complements that from tourism.
The food and parasites of fish in some deep basins of northern L. Päijänne
1982
The composition of the fish stock, food and ‘macroparasites’ were studied in eleven basins (22–100 m) of Lake Jyvasjarvi and North Paijanne in August–September 1976. The fishing was done by means of a series of nets (meshes 15, 21 and 35 mm) laid on the bottom overnight. No fish were found in the two northernmost basins owing to bad oxygen conditions caused by waste waters. Smelt and burbot were the most abundant fish in the catches in other basins but the vendace was rare. Relict crustaceans and some ‘deep water’ copepods (e.g. Heterocope borealis) played an important role in the food of fish in all basins.
Spatially structured interactions between lobsters and lobster fishers in a coastal habitat: fine-scale behaviour and survival estimated from acousti…
2013
Fishing can have profound impacts on the ecology and evolution of marine populations. Understanding population-level changes ultimately depends on knowledge about individual survival and how it varies in time and space. We used acoustic tags and a network of receivers to monitor individual behaviour and fate of European lobster (Homarus gammarus) exposed to commercial and recreational trap fisheries on the Norwegian Skagerrak coast. In August 2011, 50 male lobsters above minimum legal size were tagged and monitored before and during the lobster fishing season. We also quantified the spatial and temporal variation in fishing activity. There was no significant effect of home-range size on th…
The Use and Abuse of Sea Resources
2017
As a maritime country, the Philippines is a place of high fish consumption. Many coastal villages are populated by fishermen, who are amongst the poorest of working Filipinos. International comparisons show that the Philippine fisheries sector is mostly characterized by small inefficient fishing vessels, while some of the fishing methods are extremely destructive to the resource. Today, fishing moratoriums must be imposed in some areas to allow the reproduction of the fish. Poaching and illegal fisheries, including by foreign vessels, especially from China, plague the most important fisheries areas. Aquaculture has developed to counterbalance the decline of the natural resource, but it has …
Catch-and-release of Atlantic cod (Gadus morhua): post-release behaviour of acoustically pretagged fish in a natural marine environment
2014
Studying the sublethal effects of catch-and-release (C&R) is challenging, as there are several potential sources of bias. For example, if behavioural alterations immediately after the release event are to be studied, separation of tagging effects from actual C&R effects is required, which is a challenge in the wild, particularly in marine environments. To investigate the effects of C&R on Atlantic cod (Gadus morhua) in their natural environment, 80 cod were caught in fyke nets, fitted with acoustic transmitters, and released. After recovery from tagging and handling for at least 14 days, nine individuals were recaptured and released at least once during experimental angling, fo…
Age is not just a number – senescence affects how fish populations respond to different fishing regimes
2021
Abstract The presence of senescence in natural populations remains an unsolved problem in biology. Described as an age-dependent increase in natural mortality (known as actuarial senescence) and an age-dependent decrease in fecundity (known as reproductive senescence), the role of senescence in nature is still poorly understood. Based on empirical estimates of reproductive and actuarial senescence, we explored how senescence affects the population dynamics of Coregonus albula, a small, schooling salmonid fish. Using an empirically-based eco-evolutionary model, we investigated how the presence or absence of senescence affects how the fish population responds to pristine, intensive harvest, a…
Reply to LoganDodge: 'stable isotopes challenge the perception of ocean sunfish Mola mola as obligate jellyfish predators'.
2013
Syvaranta et al. (2012) recently provided stable-isotope data from eight small-bodied ocean sunfish Mola mola (L. 1758) captured from the Italian fishing port of Camogli on the Ligurian coast. Representative data were also given for members of pelagic and neritic–coastal food webs. The level of 13C and 15N enrichment shown by M. mola relative to their putative obligate diet of gelatinous zooplankton (gelata) (based on the locally dominant Pelagia noctiluca and literature data) was used to question their obligate consumption of such prey. Furthermore, the M. mola were isotopically more similar to neritic rather than pelagic fishes captured locally, prompting the suggestion that juvenile M. m…
Evaluating fish assemblages associated with gas platforms: Evidence from a visual census technique and experimental fishing surveys
2010
Fish assemblages associated with extractive platforms were surveyed, for the first time, using traditional fishing surveys (bottom gill net) and an underwater visual census (UVC) technique in order to test the effectiveness and to identify strengths and weaknesses of both methods. The study was carried out during three seasons at two offshore gas platforms (Eleonora and Squalo C) located in the central Adriatic Sea. Both methods recorded a similar number of fish species although with only eight species in common, thus supplying complementary information and a good estimate of the total fish species richness (39) associated with these gas platforms. The use of innovative techniques, such as …