Studies of the Fish of Great Slave Lake

1951 ◽  
Vol 8b (4) ◽  
pp. 207-240 ◽  
Author(s):  
D. S. Rawson
Keyword(s):  
Lake Trout ◽  
Mesh Size ◽  
Fish Population ◽  
Commercial Fishing ◽  
Small Fish ◽  
Fish Food ◽  
Important Species ◽  
The North ◽  
Great Slave Lake ◽  
Gill Net

A four-year study of the fish of Great Slave Lake was initiated one year before the lake was opened for commercial fishing. Information has been obtained about the composition, distribution and general ecology of the major species. Twenty-one species are listed and the ciscoes, probably of three species, await identification. Lake trout, common whitefish and ciscoes dominate the population and the former two species support an extensive gill-net fishery. The inconnu Stenodus, and the deepwater sculpin, Triglopsis, are of special zoogeographic interest.Sampling was mainly with standardized 300-yard gangs of gill net. In these, some 12,000 fish weighing about 20,000 pounds were taken. Some data were obtained on the selective effect of mesh size. Young and small fish were collected by seining.Great Slave Lake's area of 10,500 square miles includes a large open portion and two great arms, one to the north, the other extending eastward. Part of the north arm is shallow and its fish population is much like that of the main lake. Goldeyes, white suckers and pikeperch are found in the shallow warmer parts of these areas. None of these species are found in the deep and cold east arm, but in it grayling and round whitefish are numerous. The common whitefish is virtually absent from McLeod Bay at the extremity of the east arm.Data concerning growth in length and weight are provided for round whitefish, white sucker, longnose sucker, burbot and pikeperch. Most of these species grow a little slower in Great Slave Lake than in lakes farther south. Growth studies of five other important species have been undertaken by other workers.Analysis of the food of all the larger species shows that the main food chains are plankton→ cisco→ lake trout and plankton→ detritus→ bottom organisms→ whitefish. Pontoporeia, Mysis and cottids are important fish food in the deep water.Twenty-one species of parasites are recorded from ten species of fish.

Aspects of the fishery, maturation and net selectivity of the wedge sole (Dicologoglossa cuneata) off south-western Iberia: implications for fishery management

2009 ◽  
Vol 90 (7) ◽  
pp. 1465-1474 ◽  
Author(s):  
Miguel Neves Santos ◽  
Pedro Gil Lino
Keyword(s):  
Fishery Management ◽  
River Mouth ◽  
Mesh Size ◽  
Scientific Basis ◽  
Catch Per Unit Effort ◽  
Important Species ◽  
Gill Net ◽  
Catch Rates ◽  
Log Normal ◽  
First Maturity

The wedge sole (Dicologoglossa cuneata, Moreau 1881) is a commercially important species for the artisanal fleet operating off the south-western Iberian Peninsula. During 2004 and 2005 a study was undertaken aiming to provide a scientific basis for management. Data collection included information on aspects of the fishery, spawning season, size at first maturity, tangle and gill-net selectivity. Seven nominal mesh sizes were used (40, 45 and 50 mm tangle nets and 40, 50, 60 and 70 mm gill-nets). Spawning lasts from December to June, with peaks in March and May. Length at first maturity for females was estimated at 18.5 cm. Catch rates decreased sharply with increasing mesh size, with tangle nets providing the highest yields. The log-normal selectivity model provided the best fit for specimens that were wedged. The higher catch-per-unit-effort of the smaller mesh sizes and the modal length of the fitted selectivity curve being below the size-at-maturity for wedge sole, suggests that the 50 mm nominal mesh size tangle net is the most appropriate for ensuring the fishery sustainability. Nevertheless, the minimum legal size should increase to at least 18 cm and a time–area closure should be implemented off the Guadiana River mouth.

Effects of Gill-Net Trauma, Barotrauma, and Deep Release on Postrelease Mortality of Lake Trout

2015 ◽  
Vol 6 (2) ◽  
pp. 265-277 ◽  
Author(s):  
Elizabeth L. Ng ◽  
Jim P. Fredericks ◽  
Michael C. Quist
Keyword(s):  
Environmental Factors ◽  
Lake Trout ◽  
Mesh Size ◽  
Salvelinus Namaycush ◽  
Parameter Estimates ◽  
Fish Length ◽  
Logistic Regression Models ◽  
Elapsed Time ◽  
Gill Net ◽  
Treated Fish

Abstract Unaccounted postrelease mortality violates assumptions of many fisheries studies, thereby biasing parameter estimates and reducing efficiency. We evaluated effects of gill-net trauma, barotrauma, and deep-release treatment on postrelease mortality of lake trout Salvelinus namaycush. Lake trout were captured at depths up to 65 m with gill nets in Priest Lake, Idaho, and held in a large enclosure for 10–12 d. Postrelease mortality was the same for surface-release–and deep-release–treated fish (41%). Mixed-effects logistic regression models were used to evaluate effects of intrinsic and environmental factors on the probability of mortality. Presence of gill-net trauma and degree of barotrauma were associated with increased probability of postrelease mortality. Smaller fish were also more likely to suffer postrelease mortality. On average, deep-release treatment did not reduce postrelease mortality, but effectiveness of treatment increased with fish length. Of the environmental factors evaluated, only elapsed time between lifting the first and last anchors of a gill-net gang (i.e., lift time) was significantly related to postrelease mortality. Longer lift times, which may allow ascending lake trout to acclimate to depressurization, were associated with lower postrelease mortality rates. Our study suggests that postrelease mortality may be higher than previously assumed for lake trout because mortality continues after 48 h. In future studies, postrelease mortality could be reduced by increasing gill-net lift times and increasing mesh size used to increase length of fish captured.

scholarly journals DISTRIBUSI SPASIAL DAN TEMPORAL IKAN ENDEMIK RAINBOW SELEBENSIS (Telmatherina celebensis Boulenger) DI DANAU TOWUTI, SULAWESI SELATAN

2017 ◽  
Vol 13 (2) ◽  
pp. 95
Author(s):  
Syahroma Husni Nasution ◽  
Sulistiono Sulistiono ◽  
D. S. Sjafei ◽  
G. S. Haryani
Keyword(s):  
Aquatic Plant ◽  
Temporal Distribution ◽  
Mesh Size ◽  
Fish Population ◽  
Wide Distribution ◽  
Spatial And Temporal Distribution ◽  
Body Color ◽  
Gill Net ◽  
Lake Towuti ◽  
Intensive Fishing

Rainbow selebensis (Telmatherina celebensis) adalah salah satu jenis ikan endemik di Danau Towuti. Ikan tersebut memiliki warna tubuh yang indah dan berpotensi sebagai ikan hias air tawar yang bernilai ekonomis. Dikhawatirkan akan terjadi penurunan populasi ikan tersebut di alam akibat perubahan lingkungan dan penangkapan ikan yang intensif. Penurunan kualitas lingkungan tersebut secara tidak langsung berkaitan dengan penebangan hutan. Penelitian ini bertujuan untuk mengetahui distribusi spasial dan temporal ikan Rainbow Selebensis. Penelitian dilakukan di perairan Danau Towuti dari bulan Maret 2002 sampai dengan April 2003. Ikan ditangkap menggunakan jaring insang eksperimental (experimental gill net) dengan 4 ukuran mata jaring yaitu ¾, 1, 1¼, dan 1½ inci di 4 stasiun. Hasil penelitian menunjukkan bahwa ikan Rainbow selebensis berdistribusi luas di perairan Danau Towuti mulai dari wilayah litoral sampai dengan ke tengah danau. Jumlah ikan yang diperoleh lebih banyak dan ukuran ikan juga lebih bervariasi di stasiun yang terdapat tanaman air (stasiun I dan IV) dibandingkan di stasiun yang tidak terdapat tanaman air (stasiun II dan III). Distribusi ikan secara spasial dipengaruhi oleh kedalaman air dan tanaman air, sedangkan secara temporal dipengaruhi oleh ketinggian muka air, oksigen terlarut, dan pH. Puncak kelimpahan ikan ini ditemukan pada bulan Nopember. Rainbow selebensis (Telmatherina celebensis) is an endemic species in Lake Towuti. This species has excellent body color, which is commercialized as ornamental fishes. Concerning will be decress fish population due to change of environment and intensive fishing. Degradation of the environmental quality indirectly related the deforestation. The aim of this research is to obtain information on spatial and temporal distribution of Rainbow Selebensis in Lake Towuti on March 2002 until April 2003. The fish was captured with experimental gill net mesh size 0.75; 1; 1.25; and 1.5 inches at four stations. The result shows that Rainbow Celebensis has wide distribution in Lake Towuti from litoral zone until the middle of lake. At station where there are aquatic plant (station I and IV), the number and size of the fish were high and various compared to station where there were aquatic plant (station II and III). Spatial distribution of Rainbow selebensis was influenced by depth of water and existence of aquatic plant, while temporal distribution was influenced by water level, dissolved oxygen, and pH. The peak season abundance of the fish was in November.

scholarly journals Clay-pit systems fishfaunistic research in the Middle-Tisza

2007 ◽  
pp. 81-92
Author(s):  
Ferenc Demény
Keyword(s):  
Mesh Size ◽  
Flood Plain ◽  
Fish Population ◽  
Rehabilitation Program ◽  
Spined Loach ◽  
Important Species ◽  
Great Loss ◽  
Silurus Glanis ◽  
River Bed ◽  
Clay Pits

After the regulation of the Tisza River the chance of successful fish propagation lessened. Natural spooning places in the river almost completely disappeared. The fish have to find an adequate place for their propagation in the flood plain. The period of spooning usually coincides with flooding of the river. At this time fish try to find the flooded shallow places for spooning. These parts mostly include the clay-pits beside dams, which were accidentally established during construction of the dams. At this place the fry can find the necessary food. After decreasing the flood the fingerlings and a part of the spooners are trapped inclay-pits as these latter ones are not connected with the river bed. The clay-pits usually desiccate during the summer. The trapped fish population is eaten by water birds or harvested by the local man population. This means a great loss for reproduction of some fishspecies.Within the framework of the Regional Rehabilitation Program at Nagykörű, supported by the “WWF Hungary” and a “SAPARD project,” these clay-pits became connected with each other in a stretch of 5 km, and they were jointed to the Tisza by a collecting channel. The water level has been regulated by a flood gate so that the water enters the holes during the flood and is released later on in to the water bed.Data on fish were collected from the Nagykörű Whole System, from the Anyita pond and some isolated wholes in Szandaszöllős in 2004 and 2005. First of all fish fry and fingerling were collected and the success of spooning at these places was examined. Fry was harvested by a 60 x 80 cm sized lifting net of 2x3 mm mesh size. In other cases nets used by anglers for catching prey fishes was also used. Data were also collected from local fishermen who participated in saving the fry and fishing of Anyita pond.Of the several thousand caught fish specimens 28 species were identified, and among them 5 protected and 5 economically important species was found. Protected fishes were as follow: gudgeon (Gobio gobio), bitterling (Rhodeus sericeus amarus), weather fish (Misgurnus fossilis), spined loach (Cobitis elongatoides) and tubenosed goby (Proterorhinus marmoratus). Among economically important fishessamples of asp (Aspius aspius), carp (Cyprinus carpio), wels (Silurus glanis), pike (Esox lucius) and pikeperch (Sander lucioperca) were

scholarly journals Design and Operation of “Siklob”, a Mechanised Falling Gear Operated in Northern Iloilo, Philippines

2021 ◽  
Vol 34 (4) ◽  
Author(s):  
CHRISTIAN JAMES MORALES ◽  
Keyword(s):  
Mesh Size ◽  
Management Plan ◽  
The Philippines ◽  
Small Fish ◽  
Catch Per Unit Effort ◽  
Important Species ◽  
Gear Design ◽  
Fine Mesh ◽  
Sardinella Gibbosa ◽  
Commercially Important

Fisheries in the Philippines is multispecies, and this is seen with the wide variety of fishing gears used in major and minor fishing grounds in the country. These gears constantly face modification and development to improve catch quality, quantity, and overall efficiency. This study investigated the features of “siklob”, a mechanised falling gear operated along the municipal waters of Northern Iloilo, Philippines. Some coastal residents claimed that fishers use fine mesh nets for this gear, and this was because of some incidences of the capture of very small fish. Results of this study, however, indicate that the mesh size of nettings used for “siklob” is 4.35 cm, which is above the minimum set by the national law (3 cm). The gear is operated offshore, in a fishing vessel, with lights and fish-finding devices. The catch included an array of pelagic to benthic species, with Sardinella gibbosa (Bleeker, 1849) as the top species. The catch per unit effort values for two fishing operations were 17.40 kg.cast-1 and 16.5 kg.cast-1, respectively. If a management plan for the gear is to be implemented in the area, it would be necessary first to study the spawning seasons of commercially important species and impose closed fishing seasons. Before any attempt to ban or control the use of the gear, it is necessary first to understand the gear design, performance, and selectivity.

Growth, Maturity and Mortality in the Relatively Unexploited Lake Trout, Cristivomer namaycush, of Great Slave Lake

1954 ◽  
Vol 11 (6) ◽  
pp. 827-852 ◽  
Author(s):  
W. A. Kennedy
Keyword(s):  
Significant Variation ◽  
Lake Trout ◽  
The Other ◽  
Commercial Fishing ◽  
Bear Lake ◽  
Great Slave Lake ◽  
Class Strength ◽  
Mature Size ◽  
Commercial Size ◽  
Annual Mortality

Ages of 9,215 lake trout were determined. Length-weight and time-maturity relationships are shown. Sex ratio is 1:1. Only half the females of mature size spawn each year. There is no growth except during June to September, inclusive. There is a tremendous difference in size at a given age. Growth is much faster in one half of the lake than in the other, it is the same as or slightly slower than in lakes farther south and considerably faster than in Great Bear Lake. Seven years of commercial fishing did not increase total annual mortality by much. Mortality rate increases with age among all fish of catchable size. A given year-class probably attains maximum biomass well before most of its members reach commercial size. No significant variation in year-class strength was found.

Fish population studies using parasites from the Southeastern Pacific Ocean: considering host population changes and species body size as sources of variability of parasite communities

Parasitology ◽  
2014 ◽  
Vol 142 (1) ◽  
pp. 25-35 ◽  
Author(s):  
MARIO GEORGE-NASCIMENTO ◽  
MARCELO OLIVA
Keyword(s):  
Body Size ◽  
Host Species ◽  
Population Studies ◽  
Fish Population ◽  
Host Population ◽  
Small Fish ◽  
Total Biomass ◽  
Natural Oscillations ◽  
Important Species ◽  
Parasite Communities

SUMMARYResearch using parasites in fish population studies in the South Eastern Pacific (SEP) is summarized. There are 27 such studies (snapshots mainly) in single host species sampled at different geographic localities and at somewhat similar times. They have been devoted mainly to economically important species, though others on coastal and intertidal fish or on less- or non-commercial species provide insights on scales of temporal and spatial variation of parasite infracommunities. Later, we assess whether the probability of harbouring parasites depends on the host species body size. Our results indicate that a stronger tool for fish population studies may be developed under regular (long term) scrutiny of parasite communities, especially of small fish host species, due to their larger variability in richness, abundance and total biomass, than in large fish species. Finally, it might also be necessary to consider the effects of fishing on parasite communities as well as the natural oscillations (coupled or not) of host and parasite populations.

scholarly journals Estimating selectivity of experimental diamond (T0) and turned mesh (T90) codends in multi-species Mediterranean bottom trawl

2020 ◽  
Author(s):  
ANDREA PETETTA ◽  
BENT HERRMANN ◽  
MASSIMO VIRGILI ◽  
ROCCO De MARCO ◽  
GIOVANNI CANDUCI ◽  
...  
Keyword(s):  
Mesh Size ◽  
Bottom Trawl ◽  
Size Selectivity ◽  
Important Species ◽  
Trawl Fishery ◽  
The North ◽  
Common Squid ◽  
Commercially Important ◽  
The Mediterranean ◽  
The Difference

The effect of shifting from a diamond mesh codend (T0) to a 90° turned mesh codend (T90) on the size selectivity of seven commercially important species in the Mediterranean bottom trawl fishery was evaluated. During sea trials conducted in the north-western Adriatic, two experimental codends made of 54 mm nominal mesh size netting that differed only in mesh configuration were alternately mounted on the same trawl. Overall, the size selectivity was significantly improved for all the species analysed, shifting from T0 to T90. The difference in the average expected L50values between T90 and T0 was particularly marked in European hake (Merluccius merluccius, 21.26 vs 11.26 cm total length), common squid (Loligo vulgaris, 12.06 vs 7.88 cm mantle length) and mantis shrimp (Squilla mantis, 20.78 vs 13.35 mm carapace length). Both codends had an excessive size selectivity especially for red mullet (Mullus barbatus), Mediterranean horse mackerel (Trachurus mediterraneus) and whiting (Merlangius merlangus), thus involving a commercial loss. These findings demonstrate the efficiency of the T90 codend tested at excluding undersized specimens, especially of hake, whose average L50was above the minimum conservation reference size of 20 cm. The adoption of this practical and inexpensive solution could help improve the management of the demersal resources targeted by the Mediterranean bottom trawl fishery.

Use of the North American Standard Gill Net for Sampling the Invasive White Perch: Information from Three Kansas Reservoirs

2021 ◽  
Author(s):  
Bryan Sowards ◽  
Micah Waters ◽  
Craig Johnson ◽  
Ben C. Neely ◽  
Daniel E. Shoup
Keyword(s):  
North American ◽  
White Perch ◽  
The North ◽  
Gill Net ◽  
American Standard

Challenges to quantifying glass eel abundance from large and dynamic estuaries

2017 ◽  
Vol 75 (2) ◽  
pp. 727-737 ◽  
Author(s):  
Sarah Walmsley ◽  
Julie Bremner ◽  
Alan Walker ◽  
Jon Barry ◽  
David Maxwell
Keyword(s):  
Large Scale ◽  
Anguilla Anguilla ◽  
Commercial Fishing ◽  
European Eel ◽  
Estuarine System ◽  
Glass Eel ◽  
The North ◽  
Adequate Sampling ◽  
South Shore ◽  
Glass Eels

Abstract European eel Anguilla anguilla recruitment into the rivers of the northeastern Atlantic has declined substantially since the 1980s. Monitoring of recruiting juveniles, or glass eels, is usually undertaken in small estuaries and rivers. Sampling of large-scale estuaries is rare, due to the size of the sampling area and the resources needed to provide adequate sampling levels. Here we describe surveys for glass eels in the UK’s largest estuarine system, the Severn Estuary/Bristol Channel. We sampled across a 20 km-wide stretch of the estuary in 2012 and 2013, using a small-meshed net deployed from a commercial fishing trawler, and the surveys yielded over 2500 glass eels. Eels were more abundant in the surface layer (0–1.4 m depth) than at depth (down to 8.4 m depth), were more abundant close to the south shore than along the north shore or middle of the estuary, and were more abundant in lower salinity water. Numbers were higher in the second year than in the first and eels were more abundant in February than April. The difficulties and logistics of sampling in such a large estuary are discussed, along with the level of resources required to provide robust estimates of glass eel abundance.

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