Comparative angler catch rates of native versus alien piscivorous fish in an invaded river fishery

Baited trap or pot fisheries are considered to have relatively few wider ecosystem effects on the marine environment, particularly when compared with towed mobile fishing gear. However, this assumption is rarely tested in the field. This study aimed to determine the composition of non-target species that occur in crustacean pots and to assess spatial and temporal differences in catches in the waters around the Isle of Man, Irish Sea. The data were collected using fishery independent surveys and a questionnaire study. Based on fishery independent surveys, a total of five taxonomic groups and 43 species occurred as by-catch. The dominant by-catch species was velvet crab Necora puber. The by-catch per unit effort (BPUE) for all of the non-target species was low particularly in comparison to towed bottom gear fisheries around the Isle of Man. BPUE of species composition varied considerably between different locations around the Isle of Man. The results of both the fishery independent and questionnaire data suggested that the by-catch rates varied with season with peak BPUE occurring in spring which then declined into autumn and winter. By-catch composition did not decrease significantly with an increasing target species catch. Overall, by-catch was low relative to target species catch which may be partially attributable to the use of escape panels in pot fisheries in the Isle of Man.

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Rapid Ecological Shift Following Piscivorous Fish Introduction to Increasingly Eutrophic and Warmer Lake Furnas (Azores Archipelago, Portugal): A Paleoecological Approach

Ecosystems ◽

10.1007/s10021-011-9423-0 ◽

2011 ◽

Vol 14 (3) ◽

pp. 458-477 ◽

Cited By ~ 18

Author(s):

Teresa Buchaca ◽

Tue Skov ◽

Susanne Lildal Amsinck ◽

Vitor Gonçalves ◽

José Manuel Neto Azevedo ◽

...

Keyword(s):

Fish Introduction ◽

Piscivorous Fish ◽

Azores Archipelago

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Size Selectivity of Diamond and Square Mesh Codends in Pelagic Herring Trawls: Only Small Herring Will Notice the Difference

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f92-234 ◽

1992 ◽

Vol 49 (10) ◽

pp. 2104-2117 ◽

Cited By ~ 38

Author(s):

Petri Suuronen ◽

Russell B. Millar

Keyword(s):

Relative Size ◽

Mesh Size ◽

The Other ◽

Size Selectivity ◽

The Difference ◽

Catch Rates ◽

Two Sides ◽

High Catch

A twin codend trawl was fished in the northern Baltic to study the size selectivity of square mesh and diamond mesh codends of 36-mm nominal mesh size. For each codend, 15 hauls were completed with a small mesh (20 mm) codend deployed on the other side of the trawl. The relative size of the catches in the two sides of the trawl varied considerably from haul to haul (the separator section was not operating properly) and selection curves were estimated from each individual haul using a method that incorporated the differences in catching efficiency of the two sides. The length of 50% retention decreased with increased catch for both the diamond and square mesh codends, although in neither case was this relationship statistically significant. Selection curves fitted to the combined haul data were asymmetric. The square mesh codend retained significantly less small herring than the diamond mesh codend, and for larger herring the two codends had similar selectivity. In both codends, most escapes occurred at the front of the catch bulge, from the upper side of the codend. At high catch rates, mesh blockage was observed for several metres ahead of the catch bulge during the later part of the tow.

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Female reproductive biology and spawning periodicity of two species of king prawns, Penaeus longistylus Kubo and Penaeus latisulcatus Kishinouye, form Queensland's East Coast Fishery

Marine and Freshwater Research ◽

10.1071/mf9880729 ◽

1988 ◽

Vol 39 (6) ◽

pp. 729 ◽

Cited By ~ 18

Author(s):

AJ Courtney ◽

MCL Dredge

Keyword(s):

Egg Production ◽

East Coast ◽

Sea Water ◽

Coastal Region ◽

Ovary Development ◽

Commercial Catch ◽

Ovary Weight ◽

Species Population ◽

Spawning Periodicity ◽

Catch Rates

In the coastal region of central Queensland female red-spot king prawns, P. longistylus, and the western or blue-leg king prawns, P. latisulcatus, had high mean ovary weights and high proportions of advanced ovary development during the winter months of July and August of 1985 and 1986. On the basis of insemination, both species began copulating at the size of 26-27 mm CL, but P. longistylus matured and spawned at a smaller size than P. latisulcatus. Abundance of P. longistylus was generally three to four times greater than that of P. latisulcatus but the latter was subject to greater variation in abundance. Low mean ovary weight and low proportions of females with advanced ovaries were associated with the maximum mean bottom sea-water temperature (28.5�C) for both species. Population fecundity indices indicated that peaks in yolk or egg production (a) displayed a similar pattern for both species, (b) varied in timing from year to year for both species and (c) were strongly influenced by abundance. Generally, sample estimates of abundance and commercial catch rates (CPUE) showed similar trends. Differences between the two may have been due to changes in targeted commercial effort in this multi-species fishery.

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A fisheries management success story: the Gisborne, New Zealand, fishery for red rock lobsters (Jasus edwardsii)

Marine and Freshwater Research ◽

10.1071/mf97141 ◽

1997 ◽

Vol 48 (8) ◽

pp. 1103 ◽

Cited By ~ 19

Author(s):

Paul A. Breen ◽

Terese H. Kendrick

Keyword(s):

Fisheries Management ◽

Unit Price ◽

Success Story ◽

Management Options ◽

Structured Model ◽

Jasus Edwardsii ◽

Fishery Data ◽

Catch Rates ◽

Related Mortality ◽

Future Management

After individual quotas were imposed in 1990, the fishery for Jasus edwardsii in the Gisborne area showed continuing declines in catch and catch rate to 1993, and the total quota could not be caught in this area. There were few legal-sized but many sublegal-sized lobsters. Pots caused mortality of sublegal lobsters through handling, pot-related Octopus predation, and thefts from commercial pots. The industry, in conjunction with recreational fishers and Maori, developed a scheme to address these problems. The aim was to increase landed value to compensate for quota reductions, and to do this by landing more lobsters in winter (when prices were higher) and landing smaller lobsters (which had a higher unit price). A shortened season was designed to reduce pot-related mortality. Part of the scheme—a proposal to reduce the minimum legal size of male lobsters—caused controversy. However, the package was evaluated with a simple model and then accepted by the Minister of Fisheries. Results were substantially increased catch rates since 1993, a successful shift to a winter fishery, and a shift in length frequencies toward larger sizes. A simple size-structured model fitted to the fishery data and used to evaluate future management options is also described.

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Schooling behaviour of jack mackerel, Trachurus declivis (Jenyns), observed in the Tasmanian purse seine fishery

Marine and Freshwater Research ◽

10.1071/mf9930577 ◽

1993 ◽

Vol 44 (4) ◽

pp. 577 ◽

Cited By ~ 10

Author(s):

H Williams ◽

G Pullen

Keyword(s):

School Size ◽

East Coast ◽

Diurnal Changes ◽

Jack Mackerel ◽

Schooling Behaviour ◽

Summer Schools ◽

By Catch ◽

Catch Rates ◽

Lunar Effects ◽

Purse Seine Fishery

The seasonal, lunar and diurnal changes in schooling of jack mackerel were examined using log-book information collected from an industrial fishery off the east coast of Tasmania between 1985 and 1989. School size increased significantly from spring to autumn. The ratio between surface and subsurface schools encountered by the fishery also changed seasonally. Surface schools predominate during summer, whereas subsurface schools become more frequent during autumn. The fishery was predominantly a day fishery and no lunar effects on catch rates or fishing intensity were detected. Catches mainly comprised jack mackerel, although redbait (Emmelichthys nitidus Richardson) and blue mackerel (Scomber australasicus Cuvier) were a significant by-catch. In summer, schools were almost exclusively composed of jack mackerel, but in other seasons mixed schools were found. Data presented, together with evidence from other sources, suggest that the availability of schools to the fishery may be closely related to the availability of feed.

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Postsmolt Atlantic Salmon (Salmo salar) in the Labrador Sea

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f91-001 ◽

1991 ◽

Vol 48 (1) ◽

pp. 2-6 ◽

Cited By ~ 40

Author(s):

D. G. Reddin ◽

P. B. Short

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Age Distribution ◽

Labrador Sea ◽

Scale Reading ◽

Gill Nets ◽

Atlantic Salmon Salmo Salar ◽

Catch Rates ◽

Abundance And Distribution ◽

High Catch

In order to learn more about the existence, abundance, and distribution of postsmolt Atlantic salmon (Salmo salar) in the Labrador Sea, exploratory fishing was done with surface-set gill nets in early autumn of 1987 and 1988. In total, there were 468 salmon of various sea ages captured, of which 207 were postsmolts. The high catch rates compared with catch rates from Greenland suggest that the population of postsmolts in the Labrador Sea may be large. Postsmolts from rivers in Maine to Labrador were caught in the Labrador Sea, as indicated by Carlin tags and river age distribution from scale reading. The highest catch rates of postsmolts occurred in the Labrador Sea between 56° and 58°N latitude.

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