Aggregation dynamics in penaeid fisheries: banana prawns (Penaeus merguiensis) in the Australian Northern Prawn Fishery

1999 ◽  
Vol 50 (7) ◽  
pp. 667 ◽  
Author(s):  
David J. Die ◽  
Nick Ellis
Keyword(s):  
Fishing Season ◽  
Stock Size ◽  
The Status ◽  
Apparent Decrease ◽  
Average Biomass ◽  
Logbook Data ◽  
Penaeus Merguiensis ◽  
Northern Prawn Fishery ◽  
Stock Abundance

In the Gulf of Carpentaria, banana prawns (Penaeus merguiensis) form dense aggregations that are targeted by trawl vessels with the help of small aeroplanes and colour sounders. Such aggregating behaviour is rare in penaeids and may lead to a change in catchability when stock abundance changes. Commercial logbook data containing trawl-tow records have been used to identify the location, time of capture and biomass of over 600 banana prawn aggregations during 1991–92. The number of aggregations decreased by 83% in the first three weeks of the fishing season. The average biomass of an aggregation decreased even more rapidly than the number of aggregations and, after three weeks of fishing, it had been reduced by 93%. The apparent decrease in the biomass of aggregating prawns during the first three weeks of the season is, therefore, in the order of 99%. This is considerably greater than the 66% decrease that can be estimated from catch per unit of effort data. It also suggests that catchability is directly related to stock abundance. Assessment models that assume that catchability is independent of stock size may not be appropriate for the assessment of the status of common banana prawns in this fishery.

scholarly journals Modelling in-season pulses of recruitment and hyperstability-hyperdepletion in the Loligo gahi fishery around the Falkland Islands with generalized depletion models

2012 ◽  
Vol 69 (8) ◽  
pp. 1403-1415 ◽  
Author(s):  
Rubén H. Roa-Ureta
Keyword(s):  
Time Series ◽  
Basic Assumption ◽  
Fishing Effort ◽  
Predictor Variables ◽  
Falkland Islands ◽  
Response Variable ◽  
Fishing Season ◽  
Linear Relationships ◽  
Catch Rates ◽  
Stock Abundance

Abstract Roa-Ureta, R. H. 2012. Modelling in-season pulses of recruitment and hyperstability-hyperdepletion in the Loligo gahi fishery around the Falkland Islands with generalized depletion models. – ICES Journal of Marine Science, 69: . The time-series of daily catch, fishing effort, and mean body mass of the summer fishing seasons of the squid, Loligo gahi, in the Falkland Islands from 1990 to 2009 are investigated with generalizations of depletion models that account for in-season pulses of recruitment (i.e. open populations) and non-linear relationships between catch as the response variable, and effort and abundance as the predictor variables. Two main results were found. First, stock dynamics are more complex than assumed by Leslie–Davis or De Lury depletion models, because in most years, there are several major in-season recruitment pulses, sometimes even larger than the pre-season pulse, contradicting the basic assumption of a decline in catch rates over the fishing season. Second, the fishery operates under a regime of hyperstability—catch rates decline slower than abundance—at low stock abundance and hyperdepletion—catch rates decline faster than abundance—at intermediate and high stock abundance. The hyperdepleted regime is far more prevalent, a result attributed to the availability of refuges from fishing operations, which may lower the abundance threshold to pass from the low-abundance hyperstable regime to the higher-abundance hyperdepleted regime.

scholarly journals Characterization and standardization of the Atlantic albacore French pelagic trawl fishery

2018 ◽  
Vol 31 ◽  
pp. 27
Author(s):  
Natacha Nikolic ◽  
Matthew Lauretta ◽  
Audrey Patucca ◽  
Gilles Morandeau
Keyword(s):  
North Atlantic ◽  
Stock Assessment ◽  
Sea Surface ◽  
Seasonal Effects ◽  
Trawl Fishery ◽  
Generalized Linear Modelling ◽  
Linear Modelling ◽  
Logbook Data ◽  
Stock Abundance

We compiled and analysed logbook data from the French trawl albacore fishery covering the period 1991–2015. The dataset comprised catch and effort data for the French fleet operating in the Bay of Biscay and Celtic Sea, as well as spatiotemporal and gear characteristics. Generalized linear modelling was used to model spatial, seasonal, environmental, and gear covariates of fleet CPUE rates. A long-term index of relative abundance is provided that can be integrated into the stock assessment of North Atlantic albacore. The analysis revealed higher albacore CPUE associated with relatively low sea surface temperature and distinct seasonal effects. The derived abundance trend for the French trawl fishery agreed with the estimated time series of stock abundance from recent assessments.

scholarly journals Sensitivity of predicted cohort size and catches to errors in estimates of fishing mortality in the terminal year

2008 ◽  
Vol 65 (7) ◽  
pp. 1227-1234 ◽  
Author(s):  
Jan Horbowy
Keyword(s):  
Baltic Sea ◽  
Status Quo ◽  
Prediction Errors ◽  
Fishing Mortality ◽  
Random Errors ◽  
Cohort Size ◽  
Stock Size ◽  
The Status ◽  
Gulf Of Riga ◽  
Projection Error

Abstract Horbowy, J. 2008. Sensitivity of predicted cohort size and catches to errors in estimates of fishing mortality in the terminal year. – ICES Journal of Marine Science, 65: 1227–1234. Formulae for the sensitivity of projected cohort size and catches to errors (bias) in estimates of fishing mortality in the terminal year were developed. Assessment models allowing for random errors in the observed catches as well as models in which catches are treated as exact were considered. The formulae were applied to a Gulf of Riga (Baltic Sea) herring assessment to show how well they estimated prediction errors and to evaluate the effect of assessment errors on predictions. The errors propagate quickly with time, and the higher the fishing mortality, the bigger the projection error. The errors in predicted catches are somewhat lower than the errors in predicted cohort sizes. The formulae developed show that with moderate error in estimated fishing mortality (20%), the errors in predicted cohort size can reach 100%, and the errors in predicted catches may be 50% for fishing mortality estimated at 1.0 in the terminal year and the status quo prediction. As the Gulf of Riga herring case demonstrates, the overall error in predicted stock size and catches may be lower when terminal fishing mortality is underestimated at some ages and overestimated at others (cancelling effect).

Reducing impacts of trawling on protected sea snakes: by-catch reduction devices improve escapement and survival

2009 ◽  
Vol 60 (8) ◽  
pp. 824 ◽  
Author(s):  
David A. Milton ◽  
Gary C. Fry ◽  
Quinton Dell
Keyword(s):  
Crew Member ◽  
Western Pacific ◽  
Small Fish ◽  
Separate Study ◽  
Sea Snake ◽  
Fishing Season ◽  
Sea Snakes ◽  
Paired Control ◽  
By Catch ◽  
Northern Prawn Fishery

Sea snakes (Hydrophidae) are by-catch of prawn trawling throughout the tropical Indo-western Pacific. We tested the effectiveness of three by-catch reduction device (BRD) types set at different distances from the codend in Australia’s Northern Prawn Fishery (NPF). Trained crew-member observers compared the numbers of sea snakes caught in paired Control and Treatment nets in 1365 trawls. Catches of sea snakes were reduced by 43% on those vessels where a Fisheye BRD was positioned less than 70 meshes from the codend. A separate study with a scientific observer undertook trials with a ‘popeye’ Fishbox BRD. This BRD reduced sea snake catch by 85% and small fish by-catch by 48%. Catches of target prawn were similar for all nets in both studies (difference <2%). Adoption of the more effective BRDs (‘popeye’ Fishbox or Fisheye BRDs) by the NPF and locating them within 70 meshes of the codend can potentially reduce sea snake catch and thus their mortality from ~7000 in the 2007 fishing season to as few as 1500 snakes. Our study shows that the use of BRDs in tropical coastal demersal fisheries and positioning them closer to the codend will greatly reduce the catch of vulnerable sea snakes.

scholarly journals Effects of fish density distribution and effort distribution on catchability

2006 ◽  
Vol 64 (1) ◽  
pp. 178-191 ◽  
Author(s):  
Nick Ellis ◽  
You-Gan Wang
Keyword(s):  
Density Distribution ◽  
Fish Density ◽  
Catch Per Unit Effort ◽  
Commercial Catch ◽  
Aggregation Index ◽  
Management Advice ◽  
Analytical Expressions ◽  
Northern Prawn Fishery ◽  
Stock Abundance ◽  
Effort Distribution

Abstract Ellis, N., and Wang, Y-G. 2007. Effects of fish density distribution and effort distribution on catchability – ICES Journal of Marine Science, 64, 178–191. The effects of fish density distribution and effort distribution on the overall catchability coefficient are examined. Emphasis is also on how aggregation and effort distribution interact to affect overall catch rate [catch per unit effort (cpue)]. In particular, it is proposed to evaluate three indices, the catchability index, the knowledge parameter, and the aggregation index, to describe the effectiveness of targeting and the effects on overall catchability in the stock area. Analytical expressions are provided so that these indices can easily be calculated. The average of the cpue calculated from small units where fishing is random is a better index for measuring the stock abundance. The overall cpue, the ratio of lumped catch and effort, together with the average cpue, can be used to assess the effectiveness of targeting. The proposed methods are applied to the commercial catch and effort data from the Australian northern prawn fishery. The indices are obtained assuming a power law for the effort distribution as an approximation of targeting during the fishing operation. Targeting increased catchability in some areas by 10%, which may have important implications on management advice.

Factors affecting the catch rates and relative abundance of sea snakes in the by-catch of trawlers targeting tiger and endeavour prawns on the northern Australian continental shelf

2000 ◽  
Vol 51 (2) ◽  
pp. 155 ◽  
Author(s):  
T. M. Ward
Keyword(s):  
Continental Shelf ◽  
Relative Abundance ◽  
Sampling Effort ◽  
Sea Snake ◽  
Factors Affecting ◽  
Sea Snakes ◽  
The Status ◽  
By Catch ◽  
Catch Rates ◽  
Northern Prawn Fishery

A total of 4378 sea snakes (14 species; 5 unidentified specimens) were collected from 21 082 h of sampling effort by trawlers of the Northern Prawn Fishery. Most species (12) were collected from the southern Gulf of Carpentaria. Hydrophis elegans and Disteira major were caught frequently in all areas. The catch rates of H. elegans and Lapemis hardwickii were highest in the eastern gulf and in depths of 31–40 and <20 m respectively. Hydrophis elegans represented >27% of specimens from most areas. Other species that represented ≥20% of specimens from one or more areas were: L. hardwickii, H. ornatus, D. major and Aipysurus eydouxii. Catch rates of all species of snakes combined did not differ significantly between 1984–86 and 1989–90, and were moderately high around Groote Eylandt where the fishery is centred. Most by-catch species occur in areas that are not subjected to extensive trawling, and there are no data to suggest that this fishery seriously threatens any population of sea snake. However, sea snakes may be more vulnerable to trawler-induced effects than most other by-catch species, and formal assessment of the status of populations is needed.

Causes of Density-Dependent Catchability for Georges Bank Haddock Melanogrammus aeglefinus

1990 ◽  
Vol 47 (2) ◽  
pp. 385-394 ◽  
Author(s):  
Victor Crecco ◽  
William J. Overholtz
Keyword(s):  
Search Time ◽  
Curvilinear Relationship ◽  
Melanogrammus Aeglefinus ◽  
Georges Bank ◽  
Commercial Fishery ◽  
Commercial Catch ◽  
Stock Size ◽  
Stock Biomass ◽  
Haddock Melanogrammus Aeglefinus ◽  
Stock Abundance

We used population estimates (VPA) fishing effort and catch data for Georges Bank haddock, Melanogrammus aeglefinus, from 1964 through 1984 to test Paloheimo and Dickie's hypothesis which predicts: (1) that the catchability coefficient (q) from the commercial fishery is inversely related to haddock stock size (N) and stock area (Area); (2) that commercial catch per effort (C/f) data are curvilinearly related to stock abundance; and (3) that search time in the Georges Bank haddock fishery is inversely related to stock abundance. The catchability coefficients for the Georges Bank trawl fishery were inversely related to haddock stock size (r = −0.82, P < 0.001) and stock area (r = −0.75, P < 0.001). There was also a significant curvilinear relationship between commercial C/f and absolute and relative haddock stock biomass from 1964 through 1984. The slope estimate (B + 1) from this relationship was less than 1.0 (r = 4.18 to 8.95, P < 0.001), indicating nonlinearity between C/f and N. Finally, the relative search time expended by the haddock commercial fishery was inversely related to stock size from 1964 through 1984 (r = −0.75, P < 0.001). These results are consistent with the three predictions of the Paloheimo and Dickie hypothesis, suggesting that fishing mortality rates on Georges Bank haddock are a depensatory function of stock biomass.

Sea snake by-catch of prawn trawlers on the northern Australian continental shelf

1996 ◽  
Vol 47 (4) ◽  
pp. 631 ◽  
Author(s):  
TM Ward
Keyword(s):  
Data Collection ◽  
Continental Shelf ◽  
Total Catch ◽  
Sea Snake ◽  
Sea Snakes ◽  
Cape York ◽  
By Catch ◽  
Penaeus Merguiensis ◽  
Northern Prawn Fishery

This paper describes and compares the sea snakes caught by vessels that target tiger prawns and endeavour prawns or that target the banana prawns Penaeus merguiensis and P. indicus. In 1989-90, 5203 sea snakes (14 species; 7 unidentified specimens) were purchased from fishers who trawled between Koolan Island and Cape York and participated in a dedicated carcass-tagging and data-collection programme. Hydrophines (11 species) represented 86.7% of the total catch. Aipysurines (3 species) represented 15.0% of specimens from vessels that targeted tiger prawns or endeavour prawns, but only 1.1% of specimens from vessels that targeted the banana prawns P. merguiensis and P. indicus. Prawn trawlers that operated between Koolan Island and Cape York during 1990 caught approximately 81 080 (� 13 670) sea snakes. Vessels that targeted tiger/endeavour prawns, P. merguiensis and P. indicus caught approximately 69260 (� 8750), 7200 (� 3250) and 4620 (� 1120) sea snakes respectively. The results emphasize the advantages of interactions between fishers and scientists and the need to assess separately the impacts of the three fisheries that constitute the northern prawn fishery.

scholarly journals Analysis of The Potential Banana Prawn (Penaeus merguiensis) in The Northern Waters of Rembang Regency

2021 ◽  
Vol 12 (1) ◽  
pp. 73-88
Author(s):  
Muhamad Fathikul Umam ◽  
Agus Suherman ◽  
Kukuh Eko Prihantoko
Keyword(s):  
Literature Review ◽  
Secondary Data ◽  
Bottom Trawl ◽  
Primary Data ◽  
Utilization Rate ◽  
Fishing Gear ◽  
Fishing Season ◽  
Production Values ◽  
Trawl Fishing ◽  
Penaeus Merguiensis

This study aims to describe the characteristics of mini bottom trawl fishing gear and fishing season, as well as to estimate the stock density and sustainable potential of banana prawn (Penaeus merguiensis), in Rembang Regency. This study was conducted from September to October 2020, in the Northern Waters of Rembang Regency, with an area of ​​1409.7 km², using both primary and secondary data. Primary data was collected directly from observations, measurements, and interviews with fishermen, while secondary data, including data on the number and types of fishing gear, as well as production and production values, was obtained through a literature review. The results of the study found that banana prawn in the northern waters of Rembang Regency was caught using two types of fishing gear, and these are sotok/mini bottom trawls and trammel nets. The total length of mini bottom trawl in this study are 15.77 m, 16.5 m, 20.44 m, and 25.2 m. The fishing season for banana prawn is from June to September The average stock density value is 16.22 kg/km² (range 4.37 to 41.14 kg/km²), the Cmsy value is 2.625 kg, the Emsy value is 4.172 trips and the average utilization rate is 44% (range 23 to 82%). Keywords: Rembang, banana prawn, stock density, and MSY.

scholarly journals Assessment of offshore shrimp stocks of Bangladesh based on commercial shrimp trawl logbook data

2018 ◽  
Vol 65 (1) ◽  
Author(s):  
Suman Barua ◽  
Arni Magnusson ◽  
Nasiruddin MD Humayun
Keyword(s):  
Confidence Intervals ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Assessment Model ◽  
Catch Per Unit Effort ◽  
Harvest Rate ◽  
Stock Size ◽  
Considerable Uncertainty ◽  
Logbook Data

This study presents the results of analytical assessment of offshore shrimp stock in Bangladesh marine waters. A time series of annual catch per unit effort (CPUE) was derived from commercial logbook data during the period from 1986 to 2016 and used as a turning series for a Schaefer biomass model. The current stock size and annual harvest rate were estimated to be around 20300 t and 20% respectively, with the stock size increasing in the last ten years. The estimated maximum sustainable yield (MSY) reference points with 95% confidence intervals are optimal biomass BMSY = 15800 t (11300-22000 t) and optimal harvest rate uMSY = 30% (21-42%). The average annual catch was 4650 t, close to the estimated MSY of 4710 t (4570-4860 t). Overall, the stock is estimated to be in a good state and the data show that CPUE in recent years is slightly above the long-term average. The assessment results are subject to considerable uncertainty, reflected in wide confidence intervals around the estimated stock status. Moreover, the simple assessment model has restrictive assumptions that may not capture the underlying dynamics of the Bangladesh shrimp fishery, a multispecies tropical fishery with changes in the fleet composition and fishing technology. Nevertheless, the model fits well to the CPUE data and the assessment is a valuable basis for giving short-term and long-term management advice.

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