scholarly journals Stalked barnacle (Pollicipes pollicipes) harvesting in the Berlengas Nature Reserve, Portugal: temporal variation and validation of logbook data

2009 ◽  
Vol 67 (1) ◽  
pp. 19-25 ◽  
Author(s):  
David Jacinto ◽  
Teresa Cruz ◽  
Teresa Silva ◽  
João J. Castro
Keyword(s):  
Temporal Variation ◽  
Nature Reserve ◽  
Marine Protected Area ◽  
Temporal Patterns ◽  
Fishing Effort ◽  
Tidal Range ◽  
Systematic Bias ◽  
Pollicipes Pollicipes ◽  
Specific Regulation ◽  
Logbook Data

Abstract Jacinto, D., Cruz, T., Silva, T., and Castro, J. J. 2010. Stalked barnacle (Pollicipes pollicipes) harvesting in the Berlengas Nature Reserve, Portugal: temporal variation and validation of logbook data. – ICES Journal of Marine Science, 67: 19–25. Stalked barnacle (Pollicipes pollicipes) exploitation at the Berlengas Nature Reserve, Portugal, by professional harvesters has been subject to specific regulation since 2000. The only available information on barnacle exploitation there comes from catch reports (logbooks) provided by the harvesters. We evaluated the quality of the logbook information, described the temporal patterns of P. pollicipes fishing effort from 2000 to 2006 based on the logbook data, and modelled the daily fishing effort in relation to variability in oceanographic conditions. Results suggest different levels of reliability for the information contained in the logbooks: (i) information on the date of harvest seems to be reliable because 83% of the observed harvest dates were also declared; (ii) information on the quantity harvested shows a large discrepancy (mean = 31.8%) between declared and observed amounts, but we believe it can be used to analyse temporal patterns of exploitation, because there was no systematic bias (under- and overreporting was to the same extent). The total quantity of barnacles harvested between 2000 and 2006 (∼16 t year−1) was closely related to the effort applied. Daily harvesting effort was considered a function of two predictive variables (significant wave height and tidal range) and of their interaction. Neither the harvesting activity nor the resource itself seems to be at risk of collapse if such levels of pressure are maintained, but efforts should be made to increase surveillance and monitoring within the marine protected area.

Variation in geographic stock area, catchability, and natural mortality of ocean shrimp (Pandalus jordani): some new evidence for a trophic interaction with Pacific hake (Merluccius productus)

1995 ◽  
Vol 52 (5) ◽  
pp. 1018-1029 ◽  
Author(s):  
Robert W. Hannah
Keyword(s):  
Mortality Rates ◽  
Fishing Effort ◽  
Trophic Interaction ◽  
Natural Mortality ◽  
Commercial Catch ◽  
Merluccius Productus ◽  
Shrimp Abundance ◽  
New Evidence ◽  
Incorrect Information ◽  
Logbook Data

Interannual variation in geographic stock area, catchability, and natural mortality of age 2 ocean shrimp (Pandalus jordani) was investigated for the years 1980–1990, using commercial catch and logbook data. Stock area changed gradually from 1980–1990, but showed wide variation, demonstrating that an assumption of constant catchability is not valid for ocean shrimp. Stock area was positively correlated with total catch, suggesting that stock area increases roughly in proportion to shrimp abundance. The time series of fishing effort and effort per unit stock area were quite different, showing that fishing effort probably gives incorrect information on time trends in ocean shrimp fishing mortality. Natural mortality rates varied widely over the study period also and were positively correlated with the abundance of age 2+ Pacific hake (Merluccius productus), a known shrimp predator. The best correlations were between natural mortality rates and the number of age 2–7 Pacific hake. Hake abundance indices that included only age 3+ fish were not significantly correlated with shrimp natural mortality rates, suggesting that if a trophic interaction exists between these two species, it may be influenced by hake recruitment events.

scholarly journals Behavioural adjustment of fish to temporal variation in fishing pressure affects catchability: an experiment with angled trout

2020 ◽  
Vol 77 (1) ◽  
pp. 188-193 ◽  
Author(s):  
Barbara Koeck ◽  
Magnus Lovén Wallerius ◽  
Robert Arlinghaus ◽  
Jörgen I. Johnsson
Keyword(s):  
Temporal Variation ◽  
Internal State ◽  
Empirical Support ◽  
Population Level ◽  
Theoretical Models ◽  
Fishing Effort ◽  
Threat Perception ◽  
Fishing Pressure ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Catch Rates

In passive fisheries, such as angling, the fishing success depends on the ultimate decision of a fish to ingest the bait, based on an individual’s internal state, previous experience, and threat perception. Fish surviving capture by anglers are known to be less vulnerable, and catch rates usually quickly decline with increasing fishing effort. Previous theoretical models have thus suggested fishing closures as a means to recover responsiveness of fish to angling gear and maintain catch rates, yet empirical support remains limited. In a controlled replicated pond experiment, we evaluated the effects of temporal variation in fishing pressure on catch rates of rainbow trout (Oncorhynchus mykiss) by simulating short-term fishing closures. Fishing closures increased catch rates and population-level catchability by reducing threat perception at the population level and allowing released individuals to return to a vulnerable state. Our experimental results show that periodic fishing closures benefit catch rates but at the risk of aggravating the likelihood of overharvesting.

scholarly journals Modelling Reef Fish Population Responses to Fisheries Restrictions in Marine Protected Areas in the Coral Triangle

2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
Divya Varkey ◽  
Cameron H. Ainsworth ◽  
Tony J. Pitcher
Keyword(s):  
Reef Fish ◽  
Marine Protected Area ◽  
Marine Ecosystem ◽  
Ecosystem Model ◽  
Fish Population ◽  
Fishing Effort ◽  
Coral Triangle ◽  
Trade Offs ◽  
Coral Reef Ecosystems ◽  
Marine Ecosystem Models

Marine ecosystem models are used to investigate marine protected area (MPA) benefits for coral reef ecosystems located in Raja Ampat, in the heart of the Coral Triangle. Field data from an integrated and diverse research project is used to develop a spatial ecosystem model using Ecopath, Ecosim, and Ecospace modelling software. The ecological and fisheries responses of a reef ecosystem to different levels of fishing effort restrictions inside MPAs are explored. The trade-offs of allowing some fisheries to operate inside the MPAs versus designating the MPAs as no-take zones are highlighted. The results show that rapid rebuilding of reef fish populations, especially the large charismatic species, requires no-take areas. Distinct trade-offs in spillover benefits are observed between partially fished and no-take MPAs.

scholarly journals Impacts of a novel shellfishing gear on macrobenthos in a marine protected area: pump-scoop dredging in Poole Harbour, UK

2017 ◽  
Vol 31 ◽  
pp. 5 ◽  
Author(s):  
Leo J. Clarke ◽  
Luciana S. Esteves ◽  
Richard A. Stillman ◽  
Roger J.H. Herbert
Keyword(s):  
Community Structure ◽  
Protected Area ◽  
Marine Protected Area ◽  
Fishing Effort ◽  
Economic Benefits ◽  
Manila Clam ◽  
Direct Result ◽  
Monitoring Site ◽  
Hediste Diversicolor ◽  
The Impact

Understanding the impact of bottom-fishing gears at various scales and intensities on habitats and species is necessary to inform management. In Poole Harbour, UK, a multiple use marine protected area, fishermen utilise a unique ̋“pump-scoop” dredge to harvest the introduced Manila clam Ruditapes philippinarum. Managers need to balance the socio-economic benefits of the fishery with ecological concerns across the region, which has required a revision of by-laws that include both spatial and temporal measures. Within an operational fishery, we used a Before-After-Control-Impact sampling design to assess the impacts of pump-scoop dredging on benthic physical characteristics and community structure in an area where there was no dredging, an area newly opened to dredging and an area subject to high levels of historic dredging. A sampling grid was used in each area to best capture any fishing effort in the newly opened area. Core samples were taken to a depth of 30 cm within intertidal mudflats. A significant loss of fine sediments was observed in the site subject to high intensity dredging and a significant change in community structure also occurred in both dredged sites throughout the study period. In the newly opened site this was characterised by a relative increase in species richness, including increased abundance of annelid worms, notably Hediste diversicolor and Aphelochaeta marioni and a decline in the abundance of the bivalve mollusc Abra tenuis. These changes, albeit relatively small, are attributed to physical disturbance as a direct result of pump-scoop dredging, although no difference in the classification of the biotope of the site was observed. This is of particular interest to managers monitoring site condition within areas under the new by-laws as the Manila clam is spreading to other protected estuaries in the region.

Temporal patterns of association between the jellyfish Catostylus mosaicus and a sphaeromatid isopod and parasitic anemone

2017 ◽  
Vol 68 (9) ◽  
pp. 1771 ◽  
Author(s):  
Joanna G. Browne ◽  
Kylie A. Pitt ◽  
Mark D. Norman
Keyword(s):  
Time Series ◽  
Life History ◽  
Temporal Variation ◽  
Temporal Patterns ◽  
Temporal Changes ◽  
Maximum Intensity ◽  
Ecological Data ◽  
History Of ◽  
Scyphozoan Jellyfish

Jellyfish form associations with a diverse fauna including parasites and commensals, yet, ecological data on these associations, particularly time series, are rare. The present study examined temporal variation in the intensities and prevalences of two symbionts, namely, a sphaeromatid isopod (Cymodoce gaimardii) and a parasitic anemone (Anemonactis clavus) of the scyphozoan jellyfish Catostylus mosaicus over a 2-year period. Jellyfish were captured from Port Phillip Bay, Victoria, Australia, approximately every 6 weeks and inspected for symbionts. The isopod occurred on C. mosaicus on 16 of the 19 sampling occasions; prevalences ranged from 5 to 85%, and were highest in summer and autumn. Intensity ranged from one to five isopods per jellyfish. Juvenile, immature and mature isopods were present. The parasitic anemone A. clavus occurred only between May and September. Prevalences were lower than for the isopod (on 5–20% of jellyfish when present) as was maximum intensity (two anemones per jellyfish). Catostylus mosaicus appears to play an important role in the life history of a suite of symbionts, and the present study is the first to examine temporal changes in the association of the jellyfish with two of these symbionts.

scholarly journals Effects of a large-scale and offshore marine protected area on the demersal fish assemblage in the Southwest Atlantic

2012 ◽  
Vol 70 (1) ◽  
pp. 123-134 ◽  
Author(s):  
Daniela Alemany ◽  
Oscar O. Iribarne ◽  
Eduardo M. Acha
Keyword(s):  
Fish Assemblage ◽  
Protected Area ◽  
Large Scale ◽  
Marine Protected Area ◽  
Demersal Fish ◽  
Fishing Effort ◽  
Fish Assemblage Structure ◽  
Target Species ◽  
Southwest Atlantic ◽  
Before And After

Abstract Alemany, D., Iribarne, O. O., and Acha, E. M. 2013. Effects of a large-scale and offshore marine protected area on the demersal fish assemblage in the Southwest Atlantic. – ICES Journal of Marine Science, 70:123–134. There are few extensive and offshore located marine protected areas (MPAs) in the world oceans and their performance is still being debated. We evaluated the effects of a large-scale offshore MPA located on the Southwest Atlantic Patagonian Shelf (43°S 63°W) on the demersal fish assemblage. Compliance of the Patagonian MPA was assessed by analysing eight years of satellite vessel monitoring system (VMS; 2000–2008) data, which showed compliance and fishing effort concentrated near the protection boundaries. MPA effects were studied by employing a five year database collected by a scientific research vessel in protected and fishing locations, before and after the MPA establishment. We assessed 152 scientific trawling stations using multivariate analysis of fish assemblage structure, fish abundance (discriminating target and non-target species), and mean size and proportion of juveniles of the target species (Argentine hake, Merluccius hubbsi). The identified MPA effects were a trend towards increasing abundance of the demersal fish assemblage, the target and non-target fish species, and hake juvenile size, and a higher proportion of juveniles aged 2+ inside the MPA. These positive trends support the case for offshore, large-scale MPAs.

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