Catch Per Unit Area Research Articles

Trophic state-dependent distribution of asari clam Ruditapes philippinarum in Japanese coastal waters: possible utilization of asari stable isotope ratios as a production indicator

AbstractAdult asari clams Ruditapes philippinarum were widely collected from 22 sampling sites including 20 clam fishery grounds in Japan in 2013 and 2014. Their δ15N and δ13C values were suggested to be an effective indicator of environmental trophic state: the stable isotopic signatures showed significant positive correlation with the 5-year (2010–2014)-mean values of total nitrogen (r = 0.691, r = 0.716) and chlorophyll a (r = 0.643, r = 0.789) calculated from the monitoring data collected by the Ministry of the Environment. Annual asari catch per unit area (CPUA) calculated from fisheries statistics scaled per unit area of each fishery ground showed significant positive correlations with trophic state parameters such as total nitrogen (r = 0.721), chlorophyll a (r = 0.800), δ15N (r = 0.732), and δ13C (r = 0.742), indicating a close relationship between asari catch and the trophic state of waters. Most clam fishery grounds in the Seto Inland Sea showed low trophic states and CPUA, indicating that recent poor asari production in these areas may be related to poor nutrient supply to the fishery environment.

Estimation of CPUE and CPUA of pufferfish (Tetraodontidae) caught by the Bottom Trawl Fishery in the eastern Mediterranean Coasts

Two indicators of pufferfish communities, catch per unit effort (CPUE) and catch per unit area (CPUA), were used with surveys of bottom trawl fishery to elucidate the level of the catch of each pufferfish species in the Mediterranean coasts of Turkey, comprising the Iskenderun Bay, Mersin Bay, and Antalya Bay. The surveys were conducted seasonally in 2019. The average rate of CPUE for Lagocephalus sceleratus, L. suezensis, L. spadiceus, and Torquigener flavimaculosus were 2.2, 0.8, 0.5, and 0.2 kg km-2, respectively that the highest CPUE values were in winter (8.0 kg km-2) for L. sceleratus and also lowest was in winter (0.08 kg km-2) for L. spadiceus. The highest and lowest CPUE values were at the depth of 20-50 m (2.7 kg km-2) for L. sceleratus and 50-80 m (0.08 kg km-2) for T. flavimaculosus, respectively. The highest CPUE values (3.5 kg km-2) were found at the sandy bottom for L. sceleratus, and the lowest one (0.01 kg km-2) was at the hardy-ground for T. flavimaculosus. The average annual CPUA of pufferfish species at the Iskenderun, Mersin, and Antalya bays was estimated as 15.6, 28.4, and 6.81 kg, respectively, with a mean value of 17.3 kg/day/boat. In multiple correspondence analysis, L. sceleratus showed a great contribution to CPUE and CPUA data. However, T. flavimaculosus revealed contribution, especially in catch numbers which were positively affected by precipitation. L. spadiceus, L. suezensis, and T. flavimaculosus were positively affected by depth, temperature, month, season, and bottom structure.

Impacts of brush pile fishing on fish biodiversity: A case study of the Shari-Goyain River in Bangladesh

Brush pile (katha), a fish aggregating device, has been widely used in the Shari-Goyain River since 2003 to congregate fish for easier catch. Katha is usually used during the winter season when the water depth decreases. Hence, this experiment was conducted from November 2018 to March 2019 on katha fishing to investigate its status and impacts on fisheries resources of the Shari-Goyain River in the Sylhet district of Bangladesh. The study was based on the hypothesis that katha fishing might have detrimental impacts to fish biodiversity and production. Data were obtained through a questionnaire-based survey, personal interviews, catch assessment (CA), focus group discussions, and key informant interviews. A total of 54 species were documented, including two exotic fish species (tilapia and common carp) and 3 species of prawn during harvesting of the kathas. The catch per unit effort (CPUE) (kg/gear/ha/person/hour) was the highest in December (1.13 ± 0.37), followed by November (1.06 ± 0.40), January (0.80 ± 0.25), February (0.71 ± 0.23), and March (0.52 ± 0.21). The catch per unit area (CPUA) (kg/ha) was the highest in November (264.66 ± 18.21), followed by December (205.05 ± 27.77), January (175.02 ± 76.04), February (147.73 ± 52.11), and March (102.08 ± 41.04) where significant differences (p < 0.05) among the months were observed. Average catch per katha in a month ranged from 41.09 ± 16.11 to 12.42 ± 5.89 kg, with a mean of 24.29 ± 11.08 kg, and a significant decrease in average catch was observed with the progression of months. The most species richness was noticed in December (38), followed by November (35), January (34), February (28), and March (25). Siluriformes (39.123%) was the most dominant order, followed by Cypriniformes (33.956%), Decapoda (14.661%), and Ovalentaria (3.278%). According to the CA and respondents’ perception, indiscriminate harvesting of fish by katha fishing can be a cause of fish biodiversity loss as it reduces open water catches, total production, and disturbs the ecosystem. From the research findings, it is suggested that katha fishing should be stopped for sustainable management and conservation of fisheries resources in the Shari-Goyain River. Research on the effects of katha fishing should be conducted in other open waters of Bangladesh where this type of fishing is common.

Round Goby (Neogobius melanostomus) impacts on benthic fish communities in two tributaries of the Great Lakes

Numerous fish species in the Laurentian Great Lakes have been negatively impacted by the establishment of the invasive Round Goby (Neogobius melanostomus). However, limited understanding exists as to how Round Goby has impacted small-bodied native benthic fishes after its secondary invasion into tributaries of the Laurentian Great Lakes. To investigate Round Goby impacts on darter species (family Percidae) in tributary ecosystems, catch per unit area (CPUA) of native and non-native fishes from two riverine ecosystems in Southwestern Ontario (Ausable River, Big Otter Creek) were analyzed. Spatial analyses indicated Round Goby CPUA was highest proximate to the Great Lakes, with a sharp decline in CPUA at sites upstream from each lake (Round Goby CPUA approached zero after 18 and 14 km in the Ausable River and Big Otter Creek, respectively). There was some evidence of a negative relationship between the CPUA of Round Goby and several darter species along the tributary gradients, with moderately negative co-occurrence between Round Goby and Rainbow Darter in the Ausable River and Johnny Darter and Percidae species overall in Big Otter Creek. However, overwhelming evidence of negative associations between Round Goby and all darter species was not found. The negative relationship between the CPUA of Round Goby and some darter species was observed over similar time periods since establishment but greater spatial scales than in previous studies, and therefore has important implications for understanding the ecological impacts of Round Goby in tributary ecosystems.

Catch Rates for Sturgeon Chubs and Sicklefin Chubs in the Upper Missouri River 2004–2016 and Correlations With Biotic and Abiotic Variables

Abstract A multiweek standardized sampling regime during 2004–2016 in a 60-km reach of the Upper Missouri River assessed reproduction and catch rates for Sturgeon Chub Macrhybopsis gelida and Sicklefin Chub Macrhybopsis meeki. We sampled age-0 Macrhybopsis (primarily Sturgeon Chubs, but potentially including Sicklefin Chubs) all years to indicate successful reproduction, but noted an inverse correlation of catch per unit area (CPUA) with year. There was an inverse correlation for CPUA of age-1+ Sturgeon Chubs with year. There was no correlation for CPUA of age-1+ Sicklefin Chubs with year, but we noted a depression in CPUA during 2010 and 2012. The study reach includes restoration directives for federally endangered Pallid Sturgeon Scaphirhynchus albus, with 245,000 hatchery-origin Pallid Sturgeon (HOPS) stocked since 1998 to supplement the declining wild stock. Pallid Sturgeon longer than 350 mm fork length transition to piscivory and are known to prey on Sturgeon Chubs and Sicklefin Chubs. We examined the hypothesis that mass additions of HOPS to the existing predator community could have population-level effects on the two chub species. Population modeling for the stocked HOPS through time yielded estimates of nearly 1,300 piscivore-sized HOPS in 2004, an increase to 26,000 HOPS in 2012, and decreasing numbers through 2016 (14,500). A negative correlation between HOPS abundance and age-0 Macrhybopsis CPUA had the best support among other candidate variables (discharge, water temperature, catch rates of Sauger Sander canadensis). We found an inverse correlation for CPUA of age-1+ Sturgeon Chubs and estimated HOPS abundance, and there was also evidence of an inverse association between age-1+ Sicklefin Chub CPUA and HOPS in the study area. Results for a 60-km reach of the Upper Missouri River suggest declining CPUA for age-0 Macrhybopsis and Sturgeon Chubs during 2004–2016 and modest recovery of Sicklefin Chubs after 2012. Although causative factors driving CPUA changes through time are not known, correlative analyses suggest that large numbers of HOPS added to the Missouri River predator community potentially influence CPUA of Sturgeon Chubs and Sicklefin Chubs in the study area. Testing this hypothesis will require expanded quantification of chub populations and HOPS numbers through time.

Catch Per Unit Area (CPUA) estimation and distribution pattern of pharaoh cuttlefish from North Coast of Gulf of Oman

Catch Per Unit Area (CPUA) estimation and distribution pattern of pharaoh cuttlefish from North Coast of Gulf of Oman

Biodiversity and biomass of bentho-demersal megafaunal assemblages of the yellow and red squat lobster fishing grounds in Central Chile (Eastern Pacific Ocean)

Biodiversity and biomass patterns of megafaunal assemblages were assessed from the yellow (Cervimunida johni) and red (Pleuroncodes monodon) squat lobster fishing grounds in the Southeastern Pacific Ocean during four years. Bottom trawls were conducted applying the swept-area method in a stratified sampling design, obtaining global and specific catch per unit area (CPUA). We recorded two target and 47 by-catch species, with a total CPUA of 80.000 t/km2 (cumulative from 2005 to 2008) Fishes and crustaceans dominated over other taxonomic groups. Classes Actinopterygii and Malacostraca attained the highest specific richness; the presence of a few dominant and many rare species in terms of CPUA and frequency, was characteristic of the studied assemblages, hence, the general CPUA pattern parallels that of the most abundant species in the bathymetric and latitudinal gradients. The three most conspicuous non-target species, Heterocarpus reedi, Merluccius gayi gayi and Hippoglossina macrops accounted for 91% of the by-catch CPUA, whereas Class Malacostraca also represented 91% of the total CPUA. The highest average specific richness occurred at intermediate depths (300–400 m) and the lowest in shallow waters (50–100m); the highest overall CPUA occurred at 100–200m and the lowest at both 400–600m and 50–100m. Depth was the most significant factor in the variability of our assemblages. However, particular features of the Humboldt Current System might act as drivers of important effects across the latitudinal gradient on the high productivity and dynamism of the squat lobster fishery, despite the homogeneous composition of the community. This study shows the importance of considering the whole biodiversity within appropriate management actions, in order to achieve ecological benefits (e.g. resilience, functional diversity, water quality, primary productivity) in communities subjected to fishing pressure.

Drivers and trends in catch of benthic resources in Chilean TURFs and surrounding open access areas

Beginning in the 1990’s, Chile implemented an extensive Territorial User Rights for Fisheries (TURFs) network that now comprises nearly 1,000 TURFs. This network provides a rare opportunity to examine spatial and temporal trends in TURF use and impacts on surrounding open access areas (OAAs). In this analysis, landings of keyhole limpet (Fissurella spp.), kelp (Lessonia spp.) and red sea urchin (Loxechinus albus) were used to estimate catch-per-unit effort (CPUEs) and catch-per-unit area (CPUAs) indices inside and outside TURFs by fishing cove. For these species, CPUEs and CPUAs in 2015 were significantly higher inside TURFs. However, temporal trends analyzed with a linear mixed effects model indicate that CPUAs inside TURFs have been significantly decreasing since 2000 for keyhole limpet, red sea urchin and for loco (Concholepas concholepas), while in OAAs this measure only decreased for limpet. An elastic net regression was used to better explain catches in OAAs during 2015, including a variety of variables related to the characteristics and activity of proximal TURFs. Results indicate that exogenous factors unrelated to TURF management were the primary drivers of catches in OAAs during 2015 but that factors related to proximal TURFs appear to have a slight negative impact that grows over time. Collectively, these results indicate that while TURFs are associated with higher catch rates than surrounding OAAs, catch rates appear to be decreasing over time and, though limited, the impact of TURFs on surrounding OAAs may be negative. These findings suggest a need for a more nuanced and dynamic approach to spatial management on benthic resources in Chile.

Interpreting biomass and catch per unit area (CPUA) to assess the status of demersal fishes in Oman Sea

This study aimed to assess the biomass and catch per unit area (CPUA) of demersal fish resources in the northern part of the Oman Sea based on trawl survey. The study area was stratified into five stratum (I, II, III, IV and V) covering the depth layers of 10-20, 20-30, 30-50 and 50-100 m. A total number of 68 stations were monitored during the study period. The highest values of biomass were belong to stratum V and IV in the east coast of the Oman Sea and the highest species biomass was belong to batoid fishes (8054.4 tons). The lowest CPUA was recorded in the central region of the study area (stratum III, approximately 8212 kg/nm 2 ) and the highest CPUA was on both sides of the study area (the east and west coast). Moreover, the highest CPUA (2031 kg/nm 2 ) was observed in 20-30 m depth layer. The results showed the changes in biomass and CPUA based on different depths and the most abundant species groups were Trichiurus lepturus (50-100 meter), Sphyraena jello (30-50 meters), Caranx ignobilis (20-30 meters), and Pomadasys kaakan (10-20 meters).

Estimation of CPUE and CPUA of three caught fish by bottom trawler in the Motaf fishing grounds, Bushehr Province, Persian Gulf, Iran

Seyed Hosseini SM, Paighambari SY, Pouladi M, Shabani MJ. 2018. Estimation of CPUE and CPUA of three caught fish by bottom trawler in the Motaf fishing grounds, Bushehr Province, Persian Gulf, Iran. Biodiversitas 19: 1434-1440. This study was conducted to estimate catch per unit effort (CPUE) and catch per unit area (CPUA) of Giant trevally (Caranx ignobilis Forsskål, 1775), Bigeye scad (Selar crumenophthalmus (Bloch, 1793), and Sulphur goatfish (Upeneus sulphureus (Cuvier, 1829). Sampling operations were done by a stern trawler in the Motaf fishing grounds located in the Persian Gulf during summer 2016. Overall, 36 hauls were done in two depths of 50-60 m and 60-70 m. In this research, the highest length frequencies of C. ignobilis, S. crumenophthalmus, and U. sulphureus were in the length classes of 56.5-61.5, 22-23.5 and 14-15.5 cm, respectively. The results of CPUE for C. ignobilis, S. crumenophthalmus, and U. sulphureus were 3, 0.159 and 0.078 kg h-1, while the results of CPUA were 45.03, 2.44 and 1.91 kg km-2, respectively. Also, CPUE values for mature and immature forms of C. ignobilis were 5.05 and 0.65 kg h-1, for S. crumenophthalmus were 0.2 and 0.07 kg h-1, and for U. sulphureus were 0.13 and 0.04 kg h-1, and CPUA values for C. ignobilis were 22.51 and 5.02 kg km-1, for S. crumenophthalmus were 22.03 and 10.95 kg km-1, and for U. sulphureus were 27.4 and 12.77 kg km-1 at the depths of 50-60 m and 60-70 m, respectively. Finally, it was concluded that effective fishing of C. ignobilis and U. sulphureus is affordable at depths above 60-70 m, and it was not different for S. crumenophthalmus at fishing depths.

Standardization of the catch per swept area (CPUA) for direct stock assessment cruises of nylon shrimp (Heterocarpus reedi) (1998-2006)

This work analyzes the operational data of direct stock assessment cruises carried out on nylon shrimp (Heterocarpus reedi) off the central coast of Chile between 1998 and 2006. These data were modeled using the product of the expected CPUA (catch per unit area) for hauls with catch and the probability of catch (that is, catch greater than zero) to estimate the CPUA. A generalized linear model was applied; the model used four effects as factors: year, zone, depth layer, and year-zone interaction. The results showed that the year was the most relevant effect, followed by the year-zone interaction for each model analyzed. The effects of the year of the assessment and the probability of catch showed sustained growth during the study period. The interaction effect showed growth in the shrimp population mainly from Valparaiso southward. Moreover, we found that shrimp abundance was related positively to the probability of catch and inversely to the area of aggregation of the population. Finally, the discrepancy found between the analyzed abundance indexes and the biomass (particularly north of 32°S) due to the geomorphological characteristics of the sea floor and the diverse methodological criteria used in the "swept-area" assessment of this species leads us to we recommend CPUA modeling as the best option for obtaining a relative abundance index comparable over time and space.

Occurrence of finfish communities in trawl hauls of Atlantic Ocean in Badagry coast, Nigeria

Thirteen trawl hauls were conducted at depths ranging from 10 m – 100 m. Fifty six finfish families were observed, comprising ninety seven species from eighty two genera. Ten commercially important finfish families were identified out of which the Haemulidae had the highest number of occurrence and distribution with catch per unit area (CPUA) of 36.17 Kg/Km2. The Carangidae with CPUA of 22.09 Kg/Km2 was the lowest in abundance and distribution of the important finfish families. The total biomass estimate of finfishfrom the entire survey area under investigation was 440 tons (t). The middle stratum, S2 (30 m – 70 m) had the highest biomass followed by the land adjoining stratum, S1 (10 m -30 m) and the least stratum biomass wasobtained from the farthest stratum, S3 (70 m – 100 m). Fishing is optimized in the middle stratum, S2.

Estandarización de la captura por área barrida (CPUA) en cruceros de evaluación directa de camarón nailon (Heterocarpus reedi) (1998-2006)

This work analyzes the operational data of direct stock assessment cruises carried out on nylon shrimp (Heterocarpus reedi) off the central coast of Chile between 1998 and 2006. These data were modeled using the product of the expected CPUA (catch per unit area) for hauls with catch and the probability of catch (that is, catch greater than zero) to estimate the CPUA. A generalized linear model was applied; the model used four effects as factors: year, zone, depth layer, and year-zone interaction. The results showed that the year was the most relevant effect, followed by the year-zone interaction for each model analyzed. The effects of the year of the assessment and the probability of catch showed sustained growth during the study period. The interaction effect showed growth in the shrimp population mainly from Valparaiso southward. Moreover, we found that shrimp abundance was related positively to the probability of catch and inversely to the area of aggregation of the population. Finally, the discrepancy found between the analyzed abundance indexes and the biomass (particularly north of 32°S) due to the geomorphological characteristics of the sea floor and the diverse methodological criteria used in the swept-area assessment of this species leads us to we recommend CPUA modeling as the best option for obtaining a relative abundance index comparable over time and space.

Spillover from six western Mediterranean marine protected areas: evidence from artisanal fisheries

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 366:159-174 (2008) - DOI: https://doi.org/10.3354/meps07532 Spillover from six western Mediterranean marine protected areas: evidence from artisanal fisheries R. Goñi1,*, S. Adlerstein2, D. Alvarez-Berastegui1, A. Forcada3, O. Reñones1, G. Criquet4, S. Polti5, G. Cadiou6, C. Valle3, P. Lenfant4, P. Bonhomme6, A. Pérez-Ruzafa5, J. L. Sánchez-Lizaso3, J. A. García-Charton5, G. Bernard6, V. Stelzenmüller7, S. Planes4 1Centro Oceanográfico de Baleares - IEO - Muelle de Poniente s/n, 07015 Palma de Mallorca, Spain 2School of Natural Resources and Environment, University of Michigan, 3010 Dana Building, Ann Arbor, Michigan 48109-1115, USA 3Departamento de Ciencias del Mar y Biología Aplicada, Universidad de Alicante, Campus de San Vicente del Raspeig, Apd. 99, 03080 Alicante, Spain 4Laboratoire Ecosystèmes Aquatiques Tropicaux et Méditerranéens, UMR 5244 CNRS - EPHE - Université Via Domitia, 52 avenue Paul Alduy, 66860 Perpignan Cedex, France 5Departamento de Ecología e Hidrología, Universidad de Murcia, Campus de Epinardo 30100 Murcia, Spain 6GIS Posidonie, Parc Scientifique et Technologique de Luminy, CP 901, 13288 Marseille Cedex 09, France 7CEFAS, Pakefield Road, Lowestoft, Suffolk NR33 DHT, UK *Email: raquel.goni@ba.ieo.es ABSTRACT: This study investigated spillover (biomass export) around 6 marine protected areas (MPAs) in the western Mediterranean based on catch and effort data from artisanal fisheries. The selected MPAs were Cerbère-Banyuls and Carry-le-Rouet in France, and Medes, Cabrera, Tabarca, and Cabo de Palos in Spain. These MPAs had been functional for more than 8 yr and incorporate areas of fisheries closure and restricted use where fishing is limited. We based our study on the hypotheses that, in the presence of biomass export, (1) fishing effort would concentrate close to MPA boundaries, and (2) fishery production, expressed as catch per unit area (CPUA), would be highest near MPA boundaries and decrease with distance. We selected data from 14 ‘fishing tactics’ using gill nets, trammel nets and bottom long-lines targeting sparids, mullids, serranids, scorpaenids and palinurids. We analyzed the spatial distribution of effort, fishery production and revenues per unit area, using generalized additive models (GAMs), and we tested regression slopes of effort density and CPUA with distance to closure boundaries, using generalized linear models (GLMs). GAMs allowed us to recognize habitat discontinuities or ‘hot spots’ of high production in the vicinity of the MPAs, and to identify the extent of potential spillover effects in order to implement GLMs. We found evidence of effort concentration and high fishery production near fisheries closures for all fishing tactics analyzed and significant negative slopes for most. Revenues generally followed trends similar to CPUA. Significant negative slopes from GLM of effort density and CPUA with distance from fisheries closures were indicative of biomass export where habitats across closure boundaries had some degree of continuity. The spatial extent of spillover was consistent with species mobility and fisheries efficiency and extended 700 to 2500 m from fishery closure boundaries. Our results suggest that coastal MPAs can be an effective management tool for artisanal fisheries in the region and can be extended to the rest of the western Mediterranean, as the fishing tactics studied are typical of the region. KEY WORDS: Marine protected areas · Fisheries closures · Artisanal fisheries · Spillover · Fishing the line · Catch gradients · Mediterranean Sea Full text in pdf format PreviousNextCite this article as: Goñi R, Adlerstein S, Alvarez-Berastegui D, Forcada A and others (2008) Spillover from six western Mediterranean marine protected areas: evidence from artisanal fisheries. Mar Ecol Prog Ser 366:159-174. https://doi.org/10.3354/meps07532 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 366. Online publication date: August 29, 2008 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2008 Inter-Research.

Zero‐Inflated Modeling of Fish Catch per Unit Area Resulting from Multiple Gears: Application to Channel Catfish and Shovelnose Sturgeon in the Missouri River

AbstractFisheries studies often employ multiple gears that result in large percentages of zero values. We considered a zero‐inflated Poisson (ZIP) model with random effects to address these excessive zeros. By employing a Bayesian ZIP model that simultaneously incorporates data from multiple gears to analyze data from the Missouri River, we were able to compare gears and make more year, segment, and macrohabitat comparisons than did the original data analysis. For channel catfish Ictalurus punctatus, our results rank (highest to lowest) the mean catch per unit area (CPUA) for gears (beach seine, benthic trawl, electrofishing, and drifting trammel net); years (1998 and 1997); macrohabitats (tributary mouth, connected secondary channel, nonconnected secondary channel, and bend); and river segment zones (channelized, inter‐reservoir, and least‐altered). For shovelnose sturgeon Scaphirhynchus platorynchus, the mean CPUA was significantly higher for benthic trawls and drifting trammel nets; 1998 and 1997; tributary mouths, bends, and connected secondary channels; and some channelized or least‐altered inter‐reservoir segments. One important advantage of our approach is the ability to reliably infer patterns of relative abundance by means of multiple gears without using gear efficiencies.

Spillover of spiny lobsters Palinurus elephas from a marine reserve to an adjoining fishery

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 308:207-219 (2006) - doi:10.3354/meps308207 Spillover of spiny lobsters Palinurus elephas from a marine reserve to an adjoining fishery Raquel Goñi*, Antoni Quetglas, Olga Reñones Centro Oceanográfico de Baleares, Apdo. 291, 07080 Palma de Mallorca, Spain *Email: raquel.goni@ba.ieo.es ABSTRACT: We investigate the effects of the Columbretes Islands Marine Reserve (CIMR, Western Mediterranean) on the adjacent Palinurus elephas (Fabricius, 1787) fishery. After 9 to 12 yr of no-take protection there was a gradient of lobster density from the interior of the reserve up to a distance of about 4 km from its boundary. Catch and effort data were collected onboard commercial fishing boats in the fishery adjacent to the CIMR, and combined with catch per unit effort (CPUE) data from monitoring surveys conducted annually inside the reserve. Generalized additive (GAM) and linear (GLM) models were employed to examine the relationships of CPUE and catch per unit area (CPUA) as a function of distance to the reserve boundary. CPUE showed a significant non-linear decline with distance from the centre of the reserve, with a depression at the boundary followed by a plateau. This depression was caused by local depletion associated with concentration of fishing effort at the reserve boundary, while the plateau suggests that lobster export from the reserve is sufficient to maintain stable catch rates up to 1500 m from the boundary. Commercial catch and effort data were combined to estimate CPUA, which declined linearly with distance from the reserve. Analysis of recaptures of lobsters tagged and released inside the reserve indicates that the density gradient is caused by lobsters emigrating from the reserve. KEY WORDS: Marine reserve · Spiny lobster · Spillover · Tag-recapture · Artisanal fisheries · Western Mediterranean Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 308. Online publication date: February 16, 2006 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2006 Inter-Research.

The relationship between multi-species catch and effort: Among fishery comparisons

The control of fishing mortality via fishing effort remains fundamental to most fisheries management strategies even at the local community or co-management level. Decisions to support such strategies require knowledge of the underlying response of the catch to changes in effort. Even under adaptive management strategies, imprecise knowledge of the response is likely to help accelerate the adaptive learning process. Data and institutional capacity requirements to employ multi-species biomass dynamics and age-structured models invariably render their use impractical particularly in less developed regions of the world. Surplus production models fitted to catch and effort data aggregated across all species offer viable alternatives. The current paper seeks models of this type that best describe the multi-species catch–effort responses in floodplain-rivers, lakes and reservoirs and reef-based fisheries based upon among fishery comparisons, building on earlier work. Three alternative surplus production models were fitted to estimates of catch per unit area (CPUA) and fisher density for 258 fisheries in Africa, Asia and South America. In all cases examined, the best or equal best fitting model was the Fox type, explaining up to 90% of the variation in CPUA. For lake and reservoir fisheries in Africa and Asia, the Schaefer and an asymptotic model fitted equally well. The Fox model estimates of fisher density (fishers km −2) at maximum yield ( i MY) for floodplain-rivers, African lakes and reservoirs and reef-based fisheries are 13.7 (95% CI [11.8, 16.4]); 27.8 (95% CI [17.5, 66.7]) and 643 (95% CI [459,1075]), respectively and compare well with earlier estimates. Corresponding estimates of maximum yield are also given. The significantly higher value of i MY for reef-based fisheries compared to estimates for rivers and lakes reflects the use of a different measure of fisher density based upon human population size estimates. The models predict that maximum yield is achieved at a higher fishing intensity in Asian lakes compared to those in Africa. This may reflect the common practice in Asia of stocking lakes to augment natural recruitment. Because of the equilibrium assumptions underlying the models, all the estimates of maximum yield and corresponding levels of effort should be treated with caution.