Great Slave Lake: Effects of Exploitation on the Salmonid Community

1972 ◽  
Vol 29 (6) ◽  
pp. 741-753 ◽  
Author(s):  
J. J. Keleher
Keyword(s):  
Lake Trout ◽  
Fishing Effort ◽  
Study Data ◽  
Background Information ◽  
Commercial Fishery ◽  
Catch Per Unit Effort ◽  
Quota System ◽  
Great Slave Lake ◽  
Unit Effort ◽  
Average Size

A 20-year investigation commenced at the inception of the Great Slave Lake commercial fishery, and it is inferred that exploitation has been the sole cause of change in the fish stocks. Background information on the operation of the commercial fishery, the fishing regulations, and the study methods are provided. Lake whitefish, Coregonus clupeaformis, and lake trout, Salvelinus namaycush, have made up 94% of the commercial landings of 119 million lb during the period. Only three other species of the 25 occurring in the lake were usually marketed. Whitefish catches generally were distributed equally between the summer and winter seasons. Trout were caught almost exclusively during the summer season. The annual catch of these two species rose from 1.6 million lb in 1945 to a maximum of 9.4 million lb in 1949 then gradually decreased to about the 5 million lb level. The study data have been partitioned according to 13 statistical areas. Catch has not been in proportion to the extent of these areas. Whitefish catch has predominated in the western, Interior Lowlands, portion of the lake while trout catch has predominated in the eastern, Canadian Shield, portion. In various areas, the peak catches for whitefish were associated with peak catches for trout, indicating that both were the result of fishing down the virgin stocks. Summer catch per unit effort for each species has declined during the 20-year period. CPE varied with the statistical areas. The usual observed reduction for whitefish was 60% in contrast to 93% for trout. Estimated summer fishing effort and whitefish catch showed a direct relation but the relation for trout usually changed from a positive to a negative one. The average size of commercially caught fish has declined to about 2 lb for whitefish and 5 lb for trout. Information on catch per unit effort for other species indicates no evident explosions in their numbers, though ciscoes, Leucichthys spp., appear to have increased in abundance. Although the fishery was regulated in order to provide for maximum annual sustained yields, this has not been achieved for trout. Three opinions for this are offered. Exploitation under a pooled quota system for whitefish and trout is not favoured and a decrease in trout quota is recommended.

Wind-Aided Recruitment of Canadian Arctic Cisco (Coregonus autumnalis) into Alaskan Waters

1988 ◽  
Vol 45 (5) ◽  
pp. 906-910 ◽  
Author(s):  
Robert G. Fechhelm ◽  
David B. Fissel
Keyword(s):  
Time Series ◽  
Canadian Arctic ◽  
Wind Data ◽  
Commercial Fishery ◽  
Catch Per Unit Effort ◽  
Longshore Currents ◽  
Unit Effort ◽  
Colville River ◽  
Young Of The Year ◽  
Mackenzie River

Summer wind data collected at Barter Island, Alaska, were compared with commercial fishery catches of arctic cisco (Coregonus autumnalis) at the Colville River, Alaska, for the period 1967–85. There was a significant (p = 0.036) association between yearly catch-per-unit-effort and the percent of easterly winds after adjusting for a 5-yr differential in the two time series. Results suggest that young-of-the-year fish which spawn in Canada's Mackenzie River are aided in their westward dispersal into Alaskan waters via wind-driven longshore currents. The greater the prevalence of easterly winds (westerly currents), the greater the recruitment. Increased recruitment manifests itself as an increase in Alaskan commercial fishery catch some 5-yr later when fish have grown to a size that renders them susceptible to commercial nets.

scholarly journals Pêche Et Caractéristiques Morphologiques D’un Poisson-Chat Endémique Synodontis Punctifer (Daget, 1964) Dans Le Barrage Électrique De Taabo (Côte d’Ivoire)

2018 ◽  
Vol 14 (15) ◽  
pp. 101
Author(s):  
Hervé Oussou Koffi ◽  
Diaha N’guessan Constance ◽  
Soro Yaya ◽  
N’Da Konan
Keyword(s):  
Sex Ratio ◽  
Condition Factor ◽  
Morphological Characteristics ◽  
Fishing Effort ◽  
Annual Production ◽  
Allometric Growth ◽  
Catch Per Unit Effort ◽  
Large Size ◽  
Unit Effort ◽  
Significant Difference

A study of Synodontis punctifer (family: Mochokidae) of Taabo Lake was conducted from October 2015 to September 2016. This was carried out so as to evaluate its quantity (biomass) caught by fishing and also its morphological characteristics. The fish were caught using gillnets at 4 sites of the lake and different measurements were made. The fishing effort was 23 to 11 fishermen / day in Taabo city, 17 to 11 fishermen / day in Courandjourou, 13 to 5 fishermen / day in Ahondo, and 8 to 3 fishermen / day in Taabo village. The catch per unit effort (CPUE) ranged from 17.7 to 3.7 g / fisherman / day, 9.2 to 1.2 g / fisherman / day, 8.3 to 0.7 g / fisherman /day, 8 to 1g / fisherman / day at Ahondo, Courandjourou, Taabo city and Taabo village, respectively. The overall annual production was estimated at 2199.3 kg, i.e. 817 kg (40%) at Ahondo, 788.3 kg (35%) at Courandjourou, 462.5 kg (20%) at Taabo, and 131.5 kg (5%) in Taabo village. The overall sex ratio (1: 1.33) was in favor of females. Individuals have negative allometric growth at all sites with values ranging from 1.72 to 2.89. The condition factor does not vary significantly between different categories of individuals (ANOVA, F = 2.79, p ˃ 0.05). A significant difference was observed between the average sizes of the individuals of the different sites (test, p˂0,05). The large size specimens were captured at Ahondo, mean (avg = 15.38 ± 1.68 cm FL). In Courandjourou, the sizes were intermediate (avg = 13.63 ± 1.64 cm LF). Smalls sizes have been observed in Taabo city (mean= 12.37 ± 1.24 cm FL) and Taabo village (mean= 15.58 ± 1.58 cm FL).

scholarly journals Effect of hook and bait type on catch per unit effort in the Aegean Sea demersal longline fishery

2021 ◽  
Vol 38 (2) ◽  
pp. 181-188
Author(s):  
Ozan Soykan ◽  
Cemil Sağlam ◽  
İlker Aydın ◽  
Hasan Tuncay Kınacıgil
Keyword(s):  
Sparus Aurata ◽  
Length Distribution ◽  
Aegean Sea ◽  
Fishing Effort ◽  
Longline Fishery ◽  
Total Catch ◽  
Catch Per Unit Effort ◽  
Unit Effort ◽  
Catch Composition ◽  
The Impact

This study aimed to determine the impact of hook and bait type on the catch composition and catch per unit effort. Effects of hook and bait types on catch composition, catch per unit effort (CPUE), length and weight distributions in demersal longline fishery were determined by experimental surveys on demersal longline sets in the Aegean Sea. A total of 12 samplings corresponding to 4800 hook fishing effort were performed between April 2014 and September 2014. Two bait types; sardine (Sardina pilchardus) and grooved razor shell (Solen marginatus) and two hook types; J-hook and C-hook were tested. CPUE values were calculated for each species and assessed between different hook-bait combinations. A total of 623 individuals were captured belonging to 3 families and 9 species. It was found that more than 60% of total catch was captured by grooved razor shell and more than 50% of the total catch was caught with J type hook. J hook was found to be close to significant (p=0.06) and grooved razor shell was found significant (p=0.02) for CPUE. The effect of bait type was found to be more significant than that of hook type for CPUE and length distribution. Hook-bait combination differed according to species and C hook baited with sardine was determined to be the best combination for Sparus aurata as the most targeted fish in the study area. Discard ratio was calculated to be 34% in terms of weight and 42.5% in terms of total number of individuals for pooled data. The condition value (K) of the species ranged from 1.05 to 1.68 and differed according to bait type. Most of the high commercial value species caught with any hook-bait combination experimented within this study are larger than minimum fishing length according to minimum landing size regulations of Turkish fishery and maturity studies.

scholarly journals Fishing Effort and Associated Catch per Unit Effort for Small-Scale Fisheries in the Mozambique Channel Region: 1950–2016

2021 ◽  
Vol 8 ◽  
Author(s):  
Dirk Zeller ◽  
Gabriel M. S. Vianna ◽  
Matthew Ansell ◽  
Angie Coulter ◽  
Brittany Derrick ◽  
...  
Keyword(s):  
Fishing Effort ◽  
Small Scale ◽  
Catch Per Unit Effort ◽  
Important Species ◽  
Small Scale Fisheries ◽  
Mozambique Channel ◽  
Fishing Vessels ◽  
Unit Effort ◽  
Fishing Capacity ◽  
Channel Region

The Mozambique Channel region in East Africa has diverse marine ecosystems and serves as a migratory corridor for economically important species. Local and foreign industrial fisheries operate in the Mozambique Channel, but regional small-scale fisheries are the crucially important fisheries that provide food security, livelihoods, and economic opportunities for rural coastal communities. This study reconstructed and investigated trends in the fishing effort and catch per unit effort (CPUE) of small-scale marine fisheries in four Exclusive Economic Zones (EEZ) that constitute the Mozambique Channel, i.e., Union of Comoros, Madagascar, Mayotte, and Mozambique, from 1950 to 2016. Effective fishing effort for small-scale fisheries in the form of fishing capacity in kWdays (i.e., kilowatt days) was derived using the number, length, motorization (engine power) by fishing vessels, as well as an approximate human-powered equivalent for shore-based fishers without vessels, as well as days of fishing per year. Effective small-scale fishing effort in the Mozambique Channel increased by nearly 60 times from just over 386,000 kWdays in 1950 to over 23 million kWdays in 2016. Correspondingly, the overall small-scale CPUE, based on previously and independently reconstructed catch data declined by 91% in the region as a whole, from just under 175 kg⋅kWday–1 in the early 1950s to just over 15 kg⋅kWday–1 in recent years. All four EEZs showed the strongest declines in the small-scale CPUE in the earlier decades, driven by motorization and growth in vessel numbers impacting effective fishing effort. Increased motorization combined with a substantial growth in overall vessel numbers were the drivers of the increasing fishing effort and decreasing CPUE, and clearly suggest that continuing to increase the fishing capacity of small-scale fisheries in the absence of effective and restrictive management actions may exacerbate overexploitation risk.

Utilization rate of fish resources in Banggai Laut waters

2020 ◽  
Vol 1 (2) ◽  
Author(s):  
Aswad Eka Putra
Keyword(s):  
Fishing Effort ◽  
Utilization Rate ◽  
Catch Per Unit Effort ◽  
Surplus Production ◽  
Fish Resources ◽  
Unit Effort ◽  
Rate Of Increase ◽  
Increasing Trend ◽  
Fish Group ◽  
Method Approach

Capture fisheries is one of the leading sectors that drive the economy of Banggai Laut Regency. Improved fishing technology is related to fishing efforts that will affect the sustainability of fish resource stocks in the waters of Banggai Laut Regency. This study aims to identify the rate of utilization of fish resources in an effort to develop a sustainable fisheries sector in Banggai Laut waters. The method approach used is "Surplus Production". This method serves as an estimator of the relative abundance of a fish resource in the waters of Banggai Laut Regency which is based on the catch per unit of fishing effort. The results showed that the capability of the fishing fleet in Banggai Laut Regency has not been able to reach potential fishing areas. The catch per unit effort (CPUE) of fish resources in Banggai Laut Regency still shows an increasing trend with the highest rate of increase by other fish group including crustaceans and mollusks, about 0.160 tons/unit in the 2014-2016 period. Meanwhile, the catch per unit effort of the large pelagic fish group showed an increasing trend with the lowest rate of increase, about 0.001 tons/unit in the 2014-2016 period. Therefore the utilization rate of fish resources in the waters of Banggai Laut Regency is still classified as under exploited.

Postimpoundment Change in Financial Performance of the Southern Indian Lake Commercial Fishery

1984 ◽  
Vol 41 (4) ◽  
pp. 715-719 ◽  
Author(s):  
M. W. Wagner
Keyword(s):  
Financial Performance ◽  
Cash Flow ◽  
Economic Viability ◽  
Lower Grade ◽  
Commercial Fishery ◽  
Catch Per Unit Effort ◽  
Capital Costs ◽  
Unit Effort ◽  
Traditional Fishing

Since impoundment of Southern Indian Lake in 1976, two economic surveys of the summer fishery have been carried out in 1977 and 1980. These surveys revealed a decrease in cash flow per fishing enterprise of 66%, from $3362 to $1141 (1980$), so that by 1980 the average enterprise could not meet its capital costs. The reduction in cash flow was mainly attributable to decreased gross revenues, due to decreased catch per unit effort on traditional fishing grounds, an increase in the proportion of lower grade whitefish in the catch, and a decrease in the average number of days spent fishing per enterprise. Consideration of a freight subsidy paid to fishermen further accented the decrease in financial performance. It is projected that by 1981 economic viability had worsened further.

Spatio-temporal distribution of longline catch per unit effort, sea surface temperature and Atlantic marlin

2003 ◽  
Vol 54 (4) ◽  
pp. 409 ◽  
Author(s):  
C. Phillip Goodyear
Keyword(s):  
Temporal Distribution ◽  
Fishing Effort ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Fishing Mortality ◽  
Catch Per Unit Effort ◽  
Surface Temperatures ◽  
Unit Effort ◽  
Spatio Temporal ◽  
Catch Rates

Atlantic blue and white marlin are currently overfished, primarily as a result of bycatch in pelagic longlines directed at other species. One possible management measure to reduce fishing mortality on these species would be to restrict fishing effort in times and places with exceptionally high marlin catch per unit effort (CPUE). The International Commission for the Conservation of Atlantic Tunas maintains a database of catch and catch-effort statistics of participating nations. These data were analysed to determine whether the distribution of CPUE is sufficiently heterogeneous in time and space that such measures might provide meaningful management alternatives. The resulting distributions of catch rates were also contrasted with monthly average sea surface temperatures to examine the possible association between temperature and CPUE. The results show spatio-temporal heterogeneity in catch rates that may be partly explained by seasonal changes in sea surface temperatures. The time–area concentrations of high CPUE differ between the species. This observed heterogeneity might be exploited to develop alternatives for reducing fishing mortality for future management of the fisheries, but additional research is needed to refine the spatial scale of the analysis and to more fully understand the factors contributing to the observed distribution.

Changes in Mortality of Lake Trout (Salvelinus namaycush) in Michigan Waters of Lake Superior in Relation to Sea Lamprey (Petromyzon marinus) Predation, 1968–78

1980 ◽  
Vol 37 (11) ◽  
pp. 2063-2073 ◽  
Author(s):  
Richard L. Pycha
Keyword(s):  
Fishery Management ◽  
Lake Trout ◽  
Lake Superior ◽  
Petromyzon Marinus ◽  
Total Mortality ◽  
Sea Lamprey ◽  
Salvelinus Namaycush ◽  
Catch Per Unit Effort ◽  
Instantaneous Rate ◽  
Unit Effort

Total mortality rates of lake trout (Salvelinus namaycush) of age VII and older from eastern Lake Superior were estimated from catch curves of age distributions each year in 1968–78. The instantaneous rate of total mortality Z varied from 0.62 to 2.31 in close synchrony with sea lamprey (Petromyzon marinus) wounding rates on lake trout. The regression of transformed Z on the index of lamprey wounding, accounted for over 89% of the variation in lake trout mortality (r2 = 0.893). An iterative method of estimating rates of exploitation u, instantaneous rates of fishing mortality F, K (a constant relating sample catch per unit effort to population size), instantaneous normal natural mortality rate M, and instantaneous rate of mortality due to sea lamprey predation L from the sample catch per unit effort and total catch by the fishery is presented. A second method using the results of a 1970–71 tagging study to estimate the mean F in 1970–77 yielded closely similar results to the above and is presented as corroboration. The estimates of u, F, and M appear to be reasonable. F ranged from 0.17 in 1974 to 0.42 in 1969 and M was estimated at 0.26. L varied from 0.21 in 1974 to 1.70 in 1968. Management implications of various policies concerning sea lamprey control, exploitation, and stocking are discussed.Key words: lake trout, sea lamprey, lamprey control, mortality, predation, Lake Superior, fishery, management

scholarly journals Trade-offs in marine protection: multispecies interactions within a community-led temperate marine reserve

2016 ◽  
Vol 74 (1) ◽  
pp. 263-276 ◽  
Author(s):  
Leigh M. Howarth ◽  
Pascal Dubois ◽  
Paul Gratton ◽  
Matthew Judge ◽  
Brian Christie ◽  
...  
Keyword(s):  
Marine Reserve ◽  
Fishing Effort ◽  
Catch Per Unit Effort ◽  
Physical Damage ◽  
Unit Effort ◽  
Trade Offs ◽  
Commercially Important ◽  
Low Levels ◽  
Multispecies Interactions ◽  
Catch Rates

This study investigated the effects of a community-led temperate marine reserve in Lamlash Bay, Firth of Clyde, Scotland, on commercially important populations of European lobster (Homarus gammarus), brown crab (Cancer pagurus), and velvet swimming crabs (Necora puber). Potting surveys conducted over 4 years revealed significantly higher catch per unit effort (cpue 109% greater), weight per unit effort (wpue 189% greater), and carapace length (10–15 mm greater) in lobsters within the reserve compared with control sites. However, likely due to low levels of recruitment and increased fishing effort outside the reserve, lobster catches decreased in all areas during the final 2 years. Nevertheless, catch rates remained higher within the reserve across all years, suggesting the reserve buffered these wider declines. Additionally, lobster cpue and wpue declined with increasing distance from the boundaries of the marine reserve, a trend which tag–recapture data suggested were due to spillover. Catches of berried lobster were also twice as high within the reserve than outside, and the mean potential reproductive output per female was 22.1% greater. It was originally thought that higher densities of lobster within the reserve might lead to greater levels of aggression and physical damage. However, damage levels were solely related to body size, as large lobsters >110 mm had sustained over 218% more damage than smaller individuals. Interestingly, catches of adult lobsters were inversely correlated with those of juvenile lobsters, brown crabs, and velvet crabs, which may be evidence of competitive displacement and/or predation. Our findings provide evidence that temperate marine reserves can deliver fisheries and conservation benefits, and highlight the importance of investigating multispecies interactions, as the recovery of some species can have knock-on effects on others.

scholarly journals Cod catches taken by the German recreational fishery in the western Baltic Sea, 2005–2010: implications for stock assessment and management

2012 ◽  
Vol 69 (10) ◽  
pp. 1769-1780 ◽  
Author(s):  
Harry V. Strehlow ◽  
Norbert Schultz ◽  
Christopher Zimmermann ◽  
Cornelius Hammer
Keyword(s):  
Baltic Sea ◽  
Gadus Morhua ◽  
Stock Assessment ◽  
Mail Survey ◽  
Fishing Effort ◽  
Commercial Fishery ◽  
Catch Per Unit Effort ◽  
Yearly Variation ◽  
Fish Stocks ◽  
Recreational Fishery

Abstract Strehlow, H. V., Schultz, N., Zimmermann, C., and Hammer, C. 2012. Cod catches taken by the German recreational fishery in the western Baltic Sea, 2005–2010: implications for stock assessment and management. – ICES Journal of Marine Science, 69: 1769–1780. Next to the commercial fishery, the recreational fishery plays an important role in the removal of biomass from fish stocks. In this study, we present estimates of German recreational cod (Gadus morhua) catches in the western Baltic Sea between 2005 and 2010. Fishing effort was estimated using a stratified mail survey and annual sales of fishing licences. Catch per unit effort was estimated by stratified random sampling of access points and interviews about completed trips. Length distributions of cod catches were acquired by sampling recreational cod catches from charter boats and data from community fishing events. Estimates of the total cod biomass removed by the recreational fishery fluctuated between 2159 t in 2009 and 4127 t in 2005. Annual recreational fishery cod harvests accounted for a significant share of the total landings, with a yearly variation from 34 to 70% of the German commercial cod landings from the western Baltic Sea. The majority of recreational fishery cod catches were taken from private boats and charter vessels. Because of the amount and specifically the variability of the recreational catches, they are important for the assessment and management of the resource and, therefore, need to be surveyed annually.

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