scholarly journals Density-dependent growth in ‘catch-and-wait’ fisheries has implications for fisheries management and Marine Protected Areas

AMBIO ◽  
2019 ◽  
Vol 49 (1) ◽  
pp. 107-117 ◽  
Author(s):  
Julian Merder ◽  
Patricia Browne ◽  
Jan A. Freund ◽  
Liam Fullbrook ◽  
Conor Graham ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Marine Protected Areas ◽  
Marine Reserve ◽  
Growth Patterns ◽  
Fundamental Issue ◽  
Catch Per Unit Effort ◽  
Density Dependent ◽  
Negative Effect ◽  
Dependent Growth ◽  
Fisheries Enhancement

Abstract Stock enhancement activities provide an opportunity to examine density-dependent suppression of population biomass which is a fundamental issue for resource management and design of no-take-zones. We document ‘catch-and-wait’ fisheries enhancement where all but the largest lobsters are thrown back, recapturing them later after they have grown to a larger size. The residency, rate of return, and potential negative density-dependent effects of this activity are described using a combination of tagging and v-notching and by relating spatial growth patterns to population density defined with Catch Per Unit Effort. The results successfully demonstrated the concept of catch-and-wait practices. However, a density-dependent suppression of growth (in body size) was observed in male lobsters. This demonstrates a mechanism to explain differences in lobster sizes previously observed across EU fishing grounds with different stock densities. This negative effect of density could also affect individual biomass production in marine reserve or no-take zones.

Use of a marine reserve to determine the direct and indirect effects of fishing on growth in a New Zealand fishery for the spiny lobster Jasus edwardsii

2012 ◽  
Vol 69 (5) ◽  
pp. 894-905 ◽  
Author(s):  
Debbie J. Freeman ◽  
Paul A. Breen ◽  
Alison B. MacDiarmid
Keyword(s):  
Growth Rates ◽  
Marine Reserve ◽  
Spiny Lobster ◽  
Catch Per Unit Effort ◽  
Density Dependent ◽  
Time Period ◽  
Jasus Edwardsii ◽  
Negative Effect ◽  
Similar Growth ◽  
Positive Effect

The effects of fishing on growth in a spiny lobster, Jasus edwardsii , were explored by using a no-take marine reserve as a control for these effects. We analysed data from lobster tag–recapture studies outside the reserve from 1975 until the present and tag–recapture from inside the reserve during a recent 8-year study. We explored whether recent and historical data showed similar growth and, using catch per unit effort (CPUE) data from research potting and commercial returns, whether growth rates in this lobster species were affected by population density. Despite the confounded nature of the data, recent growth rates appeared to be lower than in earlier years, growth appeared weakly density-dependent, and the reserve appeared to have a positive effect on lobster growth. The strongest effect was the time period, but the density-dependent and reserve effects appeared real. The reserve effect suggests a negative effect of handling of sublegal-sized lobsters on growth.

Density-Dependent Growth of Age 1 English Sole (Parophrys vetuls) in Oregon and Washington Coastal Waters

1987 ◽  
Vol 44 (1) ◽  
pp. 48-53 ◽  
Author(s):  
Randall M. Peterman ◽  
Michael J. Bradford
Keyword(s):  
Coastal Waters ◽  
Time Trends ◽  
Annual Growth Rate ◽  
English Sole ◽  
Density Dependent ◽  
Stock Assessments ◽  
Negative Effect ◽  
Dependent Growth ◽  
Parophrys Vetulus ◽  
The Impact

We tested whether English sole (Parophrys vetulus) in Oregon and Washington waters show density-dependent growth. We found that there is a significant negative effect of cohort abundance on annual growth rate of age 1 fish, but not on growth of ages 2–7. Unlike most similar studies of density dependence, this result was not confounded by time trends in abundance and growth. The multiple regression of age 1 growth on cohort abundance and temperature accounted for 91% of the interannual variation in growth, which was a significant increase in r2 over that of the previously published relation with temperature alone. However, stock assessments which take into account only the previously published temperature effect on growth for this stock will probably not seriously overestimate the impact of management regulations which increase cohort abundance.

scholarly journals Bayesian depletion model estimates of spiny lobster abundance at two marine protected areas in Belize with or without in-season recruitment

2014 ◽  
Vol 72 (suppl_1) ◽  
pp. i232-i243 ◽  
Author(s):  
Elizabeth A. Babcock ◽  
William J. Harford ◽  
Robin Coleman ◽  
Janet Gibson ◽  
Julio Maaz ◽  
...  
Keyword(s):  
Protected Areas ◽  
Marine Protected Areas ◽  
Marine Reserve ◽  
Spiny Lobster ◽  
Fishing Mortality ◽  
Catch Per Unit Effort ◽  
Strombus Gigas ◽  
Queen Conch ◽  
Opening And Closing ◽  
Typical Model

Abstract In Belize, beginning in 2011 at Glover's Reef Marine Reserve, and in 2012 at Port Honduras Marine Reserve, fishers have been required to keep logbooks to document their catch and effort. A Bayesian depletion model including in-season recruitment was applied to the standardized catch per unit effort (cpue) of Caribbean spiny lobster (Panulirus argus) from the logbooks to estimate the abundance and fishing mortality of lobsters at both sites. Two alternative subsets of the cpue data were used to account for changes in targeting caused by the opening and closing of the queen conch (Strombus gigas) season. At Glover's Reef, a typical model estimated abundance ∼66–79 000 lobsters. Of these, ∼60–85% were present at the beginning of the season and the rest recruited into the fished population later in the season. The depletion model applied to data from the 2012 season at Port Honduras found an abundance of ∼12 000 lobsters, and in-season recruitment was not supported by the data. That in-season recruitment was present at Glover's Reef and not at Port Honduras may be explained by the fact that Glover's Reef has more unfished areas that could serve as a source of adult lobsters during the season. Glover's Reef has a larger no-take zone (20% of the reserve area, compared with 5% at Port Honduras), and it is surrounded by a deep wall reef where lobsters are found below the depth accessible to fishers. The models estimated a harvest fraction of ∼70% in both reserves.

scholarly journals The spatial scale of density-dependent growth and implications for dispersal from nests in juvenile Atlantic salmon

Oecologia ◽  
2010 ◽  
Vol 165 (4) ◽  
pp. 959-969 ◽  
Author(s):  
Sigurd Einum ◽  
Grethe Robertsen ◽  
Keith H. Nislow ◽  
Simon McKelvey ◽  
John D. Armstrong
Keyword(s):  
Atlantic Salmon ◽  
Spatial Scale ◽  
Density Dependent ◽  
Juvenile Atlantic Salmon ◽  
Dependent Growth

scholarly journals Correcting density-dependent effects in abundance estimates from bottom-trawl surveys

2014 ◽  
Vol 71 (5) ◽  
pp. 1107-1116 ◽  
Author(s):  
Stan Kotwicki ◽  
James N. Ianelli ◽  
André E. Punt
Keyword(s):  
Stock Assessment ◽  
Dead Zone ◽  
Walleye Pollock ◽  
Assessment Model ◽  
Bottom Trawl ◽  
Trawl Survey ◽  
Negative Consequences ◽  
Catch Per Unit Effort ◽  
Density Dependent ◽  
Index Of Abundance

Abstract Indices of abundance are important for estimating population trends in stock assessment and ideally should be based on fishery-independent surveys to avoid problems associated with the hyperstability of the commercial catch per unit effort (cpue) data. However, recent studies indicate that the efficiency of the survey bottom trawl (BT) for some species can be density-dependent, which could affect the reliability of survey-derived indices of abundance. A function qe∼f(u), where qe is the BT efficiency and u the catch rate, was derived using experimentally derived acoustic dead-zone correction and BT efficiency parameters obtained from combining a subset of BT catch data with synchronously collected acoustic data from walleye pollock (Theragra chalcogramma) in the eastern Bering Sea (EBS). We found that qe decreased with increasing BT catches resulting in hyperstability of the index of abundance derived from BT survey. Density-dependent qe resulted in spatially and temporarily variable bias in survey cpue and biased population age structure derived from survey data. We used the relationship qe∼f(u) to correct the EBS trawl survey index of abundance for density-dependence. We also obtained a variance–covariance matrix for a new index that accounted for sampling variability and the uncertainty associated with the qe. We found that incorporating estimates of the new index of abundance changed outputs from the walleye pollock stock assessment model. Although changes were minor, we advocate incorporating estimates of density-dependent qe into the walleye pollock stock assessment as a precautionary measure that should be undertaken to avoid negative consequences of the density-dependent qe.

scholarly journals Changes in the catch composition of artisanal fisheries attributable to dolphin depredation in a Mediterranean marine reserve

2009 ◽  
Vol 66 (4) ◽  
pp. 699-707 ◽  
Author(s):  
Delphine Rocklin ◽  
Marie-Catherine Santoni ◽  
Jean-Michel Culioli ◽  
Jean-Antoine Tomasini ◽  
Dominique Pelletier ◽  
...  
Keyword(s):  
Marine Reserve ◽  
Bottlenose Dolphins ◽  
Artisanal Fisheries ◽  
Catch Per Unit Effort ◽  
Natural Reserve ◽  
Catch Composition ◽  
The Impact ◽  
High Fish ◽  
Fishing Area ◽  
Fish Avoidance

AbstractRocklin, D., Santoni, M-C., Culioli, J-M., Tomasini, J-A., Pelletier, D., and Mouillot, D. 2009. Changes in the catch composition of artisanal fisheries attributable to dolphin depredation in a Mediterranean marine reserve. – ICES Journal of Marine Science, 66: 699–707. There is increasing evidence from previous studies, and from fishers’ observations, that coastal dolphins use fishing nets as an easily accessible feeding source, damaging or depredating fish caught in the nets. This study investigates the impact of dolphin depredation on artisanal trammelnets by analysing the catch composition of 614 artisanal fishing operations in the Bonifacio Strait Natural Reserve (France). Common bottlenose dolphins (Tursiops truncatus) attacked, on average, 12.4% of the nets and damaged 8.3% of the catch. However, attacked nets were characterized by statistically significantly higher catch per unit effort than unattacked ones. Catch composition also differed significantly after dolphin attacks; bentho-pelagic fish were more represented and reef-associated fish less represented. Our results suggest that (i) dolphins are attracted by high fish densities in the fishing area and/or nets, and (ii) their attacks induce specific fish-avoidance behaviour, according to the fish position in the water column. Although dolphins depredate a small part of the catch, damage to nets, not yet assessed in this area, could weaken the benefits that reserves can provide to artisanal fisheries.

scholarly journals Factors affecting relative abundance of low-mobility fishing resources: spiny lobster in the Galapagos Marine Reserve

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7278 ◽  
Author(s):  
Juan Carlos Murillo-Posada ◽  
Silvia Salas ◽  
Iván Velázquez-Abunader
Keyword(s):  
Monitoring System ◽  
Relative Abundance ◽  
Spatial Scales ◽  
Marine Reserve ◽  
Spiny Lobster ◽  
Fishing Effort ◽  
Additive Models ◽  
Catch Per Unit Effort ◽  
Monthly Basis ◽  
Galapagos Marine Reserve

Management of low-mobility or benthic fisheries is a difficult task because variation in the spatial distribution and population dynamics of the resources make the monitoring and assessment of these fisheries challenging. We assumed that environmental, spatial, and temporal factors can contribute to the variability of the relative abundance of such species; we used Generalized Additive Models for Location Scale and Shape (GAMLSS) to test this hypothesis using as a case study the lobster fishery (targeting two species) in the Galapagos Marine Reserve, Ecuador. We gathered data on each of the two species of lobster on a monthly basis over seven years, including: (a) onboard observers’ records of catch data, fishing effort, and ground location by trip, and (b) data from interviews undertaken with fishers at their arrival to port, recording the same type of information as obtained from onboard observers. We use this information to analyze the effect of the measured variables and to standardize the Catch per Unit Effort (CPUE) in each case, using the GAMLSS. For both species, the temperature, region, fishing schedule, month, distance, and the monitoring system were significant variables of the selected models associated with the variability of the catch rate. ForPanulirus penicillatus, CPUE was higher at night than during the day, and forPanulirus gracilisit was higher during the day. Increased temperature resulted in a decrease of CPUE values. It was evident that temporal, spatial scales and monitoring system can influence the variability of this indicator. We contend that the identification of drivers of change of relative abundance in low-mobility species can help to support the development of monitoring and assessment programs for this type of fisheries.

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