scholarly journals The status and trends of small cetacean landings at Dixcove artisanal fishing port, western Ghana

2019 ◽  
Author(s):  
Patrick K Ofori-Danson ◽  
Joseph Debrah ◽  
Koen Van Waerebeek
Keyword(s):  
Coastal Waters ◽  
Bottlenose Dolphins ◽  
Fishing Effort ◽  
Humpback Whales ◽  
Small Scale ◽  
Catch Per Unit Effort ◽  
Western Africa ◽  
Republic Of Benin ◽  
Lagenodelphis Hosei ◽  
Common Dolphins

One of the largest documented takes of small cetaceans in western Africa occurs in Western regional coastal waters of Ghana. This temporally coincided with steadily decreasing catches of finfish, especially small pelagics (sardinellas, anchovies, mackerel) over the past decades, attributed to both climate change and indiscriminate exploitation methods. Dixcove, a key fishing port for cetacean landings was surveyed during 96 days between 12 September -17 December 2018. Our goal was to update insights from our earlier surveys, especially on catch rates, catch per unit effort and species composition. A total of 57 delphinids of 10 species were observed landed: Stenella attenuata (28.1%), Stenella clymene (17.5%), Lagenodelphis hosei (10.5%), Steno bredanensis (10.5%), unidentified stenellids (8.8%), Grampus griseus (3.5%), Delphinus sp. (3.5%), Pseudorca crassidens (3.5%) and single specimens of Tursiops truncatus, Stenella longirostris and Stenella frontalis. The observed cetacean catch per diem (cpd =0.59) at Dixcove was low compared to earlier rates for this port (e.g. cpd =2.82, in 2013-2014). However, fishing effort, measured as the number of canoes landing per diem (range 0-25; mean= 8.82 ± 6.05; n=22) was also reduced. Poor fish catches forced many canoes to remain in port. The prevalence in landings of common bottlenose dolphins and common dolphins has significantly decreased in the period 2000-2018. The prevalence of Fraser's dolphins and false killer whales increased. Indications are that a higher proportion of cetacean carcasses may be utilised offshore as shark bait. Hooks baited with cetacean parts are deployed in auxiliary longlines set longside large-mesh drift gillnets with a shark aggregating purpose, a first report in Africa. Shore-based incidental sightings of humpback whales suggest the potential for small scale whale-watching ecotourism in Ghanaian coastal waters, as pertains in the nearby waters of the Republic of Benin.

scholarly journals The status and trends of small cetacean landings at Dixcove artisanal fishing port, western Ghana

2019 ◽  
Author(s):  
Patrick K Ofori-Danson ◽  
Joseph Debrah ◽  
Koen Van Waerebeek
Keyword(s):  
Coastal Waters ◽  
Bottlenose Dolphins ◽  
Fishing Effort ◽  
Humpback Whales ◽  
Small Scale ◽  
Catch Per Unit Effort ◽  
Western Africa ◽  
Republic Of Benin ◽  
Lagenodelphis Hosei ◽  
Common Dolphins

One of the largest documented takes of small cetaceans in western Africa occurs in Western regional coastal waters of Ghana. This temporally coincided with steadily decreasing catches of finfish, especially small pelagics (sardinellas, anchovies, mackerel) over the past decades, attributed to both climate change and indiscriminate exploitation methods. Dixcove, a key fishing port for cetacean landings was surveyed during 96 days between 12 September -17 December 2018. Our goal was to update insights from our earlier surveys, especially on catch rates, catch per unit effort and species composition. A total of 57 delphinids of 10 species were observed landed: Stenella attenuata (28.1%), Stenella clymene (17.5%), Lagenodelphis hosei (10.5%), Steno bredanensis (10.5%), unidentified stenellids (8.8%), Grampus griseus (3.5%), Delphinus sp. (3.5%), Pseudorca crassidens (3.5%) and single specimens of Tursiops truncatus, Stenella longirostris and Stenella frontalis. The observed cetacean catch per diem (cpd =0.59) at Dixcove was low compared to earlier rates for this port (e.g. cpd =2.82, in 2013-2014). However, fishing effort, measured as the number of canoes landing per diem (range 0-25; mean= 8.82 ± 6.05; n=22) was also reduced. Poor fish catches forced many canoes to remain in port. The prevalence in landings of common bottlenose dolphins and common dolphins has significantly decreased in the period 2000-2018. The prevalence of Fraser's dolphins and false killer whales increased. Indications are that a higher proportion of cetacean carcasses may be utilised offshore as shark bait. Hooks baited with cetacean parts are deployed in auxiliary longlines set longside large-mesh drift gillnets with a shark aggregating purpose, a first report in Africa. Shore-based incidental sightings of humpback whales suggest the potential for small scale whale-watching ecotourism in Ghanaian coastal waters, as pertains in the nearby waters of the Republic of Benin.

scholarly journals Fishing Effort and Associated Catch per Unit Effort for Small-Scale Fisheries in the Mozambique Channel Region: 1950–2016

2021 ◽  
Vol 8 ◽  
Author(s):  
Dirk Zeller ◽  
Gabriel M. S. Vianna ◽  
Matthew Ansell ◽  
Angie Coulter ◽  
Brittany Derrick ◽  
...  
Keyword(s):  
Fishing Effort ◽  
Small Scale ◽  
Catch Per Unit Effort ◽  
Important Species ◽  
Small Scale Fisheries ◽  
Mozambique Channel ◽  
Fishing Vessels ◽  
Unit Effort ◽  
Fishing Capacity ◽  
Channel Region

The Mozambique Channel region in East Africa has diverse marine ecosystems and serves as a migratory corridor for economically important species. Local and foreign industrial fisheries operate in the Mozambique Channel, but regional small-scale fisheries are the crucially important fisheries that provide food security, livelihoods, and economic opportunities for rural coastal communities. This study reconstructed and investigated trends in the fishing effort and catch per unit effort (CPUE) of small-scale marine fisheries in four Exclusive Economic Zones (EEZ) that constitute the Mozambique Channel, i.e., Union of Comoros, Madagascar, Mayotte, and Mozambique, from 1950 to 2016. Effective fishing effort for small-scale fisheries in the form of fishing capacity in kWdays (i.e., kilowatt days) was derived using the number, length, motorization (engine power) by fishing vessels, as well as an approximate human-powered equivalent for shore-based fishers without vessels, as well as days of fishing per year. Effective small-scale fishing effort in the Mozambique Channel increased by nearly 60 times from just over 386,000 kWdays in 1950 to over 23 million kWdays in 2016. Correspondingly, the overall small-scale CPUE, based on previously and independently reconstructed catch data declined by 91% in the region as a whole, from just under 175 kg⋅kWday–1 in the early 1950s to just over 15 kg⋅kWday–1 in recent years. All four EEZs showed the strongest declines in the small-scale CPUE in the earlier decades, driven by motorization and growth in vessel numbers impacting effective fishing effort. Increased motorization combined with a substantial growth in overall vessel numbers were the drivers of the increasing fishing effort and decreasing CPUE, and clearly suggest that continuing to increase the fishing capacity of small-scale fisheries in the absence of effective and restrictive management actions may exacerbate overexploitation risk.

scholarly journals Cetacean–fishery interactions in Galicia (NW Spain): results and management implications of a face-to-face interview survey of local fishers

2013 ◽  
Vol 71 (3) ◽  
pp. 604-617 ◽  
Author(s):  
Sabine Goetz ◽  
Fiona L. Read ◽  
M. Begoña Santos ◽  
C. Pita ◽  
Graham J. Pierce
Keyword(s):  
Bottlenose Dolphins ◽  
Management Strategies ◽  
Economic Loss ◽  
Fishing Effort ◽  
Purse Seine ◽  
Fishing Gear ◽  
Nw Spain ◽  
Face To Face ◽  
Fishery Interactions ◽  
Common Dolphins

Abstract Galicia (NW Spain) is an important fishing region with a high potential for cetacean–fishery interactions. Cetacean depredation on catch and damage to fishing gear can potentially lead to substantial economic loss for fishers, while cetacean bycatch raises conservation concerns. With the aim of gathering information on the types and scale of interactions and of suggesting possible management strategies, we conducted face-to-face interviews with fishers in local fishing harbours, in particular to identify specific problematic interactions and to quantify the level of economic loss and bycatch rates associated with these interactions. We found that cetacean–fishery interactions are frequent, although damage to catch and fishing gear by cetaceans was mostly reported as small. Nevertheless, substantial economic loss can result from common bottlenose dolphins (Tursiops truncatus) damaging coastal gillnets and from short-beaked common dolphins (Delphinus delphis) scattering fish in purse-seine fisheries. Cetacean bycatch mortality was reported to be highest for trawls and set gillnets, and probably exceeds sustainable levels for local common and bottlenose dolphin populations. Although interview data may be biased due to the perceptions of interviewees, and therefore should be interpreted with care, the methodology allowed us to cover multiple sites and fisheries within a reasonable time frame. Minimizing cetacean–fishery interactions requires the implementation of case-specific management strategies with the active participation of fishers. For set gillnet and purse-seine fisheries, the use of acoustic deterrent devices (pingers) may prevent cetaceans from approaching and getting trapped in the nets. For trawl fisheries, where bycatch appears to be particularly high at night in water depths of 100–300 m, possible solutions include the implementation of time/area closures and the relocation of some fishing effort to deeper waters.

scholarly journals Effects of selective fishing on a small scale multi-species and multi-gear freshwater fishery in the Magdalena River Basin (Colombia)

2021 ◽  
Author(s):  
Sandra Jeannette Hernández Barrero ◽  
Mauricio Valderrama Barco ◽  
Carlos Guillermo Barreto Reyes ◽  
Wolfgang B Stotz
Keyword(s):  
River Basin ◽  
Cost Benefit ◽  
Mesh Size ◽  
Fishing Effort ◽  
Trophic Levels ◽  
Self Control ◽  
Control Measures ◽  
Small Scale ◽  
Catch Per Unit Effort ◽  
Unit Effort

Classical management has not been able to stop the 65% decrease in fishery production during the last 40 years in the Magdalena-Cauca River Basin. To analyze the effects of selective fishing of multiple species and small scale fisheries we addressed temporal changes at fishing level and the response of fishermen. The fishery reduced production and CPUE (catch per unit effort standardized), decreased the large sizes and growth rates of Prochilodus magdalenae and Pseudoplatystoma magdaleniatum, changed the abundance of trophic levels (decreased carnivores and increase of detritivores, omnivores), and increased exploitation rates. The fishermen have responded by implementing self-control measures, diversifying fishing gear and mesh size, including new species and sizes in the catch with a higher cpue (catch per unit effort) of small sized fish, adjusting the fishing effort to the abundance. We conclude that selective fishing has had ecological effects and fishermen have empirically self-regulated to optimize the cost-benefit ratio of their activity, developing a fishery that is more in line with ecosystemic structures. We address the balanced harvest strategy as a management alternative.

scholarly journals A framework for mapping small-scale coastal fisheries using fishers' knowledge

2014 ◽  
Vol 71 (7) ◽  
pp. 1781-1792 ◽  
Author(s):  
Marc Léopold ◽  
Nicolas Guillemot ◽  
Delphine Rocklin ◽  
Cheryl Chen
Keyword(s):  
Spatial Information ◽  
New Caledonia ◽  
Fishing Effort ◽  
Marine Conservation ◽  
Geographical Information ◽  
Small Scale ◽  
Catch Per Unit Effort ◽  
Distributed Resources ◽  
Coastal Fisheries ◽  
Promising Source

Abstract Collecting spatial information on fisheries catch and effort is essential to understanding the spatial processes of exploited population dynamics and to manage heterogeneously distributed resources and uses. The use of fishers' knowledge through geographical information systems (GISs) is increasingly considered as a promising source of local information on small-scale coastal fisheries. In this paper we describe the first framework for mapping entire small-scale coastal fisheries using fishers' knowledge on catch size and fishing effort. Four mangrove and coral reef fisheries targeting invertebrates or finfish in New Caledonia (southwest Pacific) were mapped following a five-step framework: (i) stratified random sampling of regular fishers; (ii) collection of fishers' knowledge of fishing areas, fishing effort, and catch size through map-based interviews; (iii) data integration into a spatial geodatabase; (iv) statistical extrapolation of fisher data to the fishery scale; and (v) mapping of catch, effort, and catch per unit effort (CPUE) for each fishery using a GIS overlay procedure. We found evidence that fishers' knowledge supplied precise and accurate quantitative and spatial information on catch size, fishing effort and CPUE for entire fisheries. Fisheries maps captured the fine-scale spatial distribution of fishing activities in a variety of ways according to target taxa, gear type, and home ports. Applications include area-based marine conservation planning and fishery monitoring, management, and governance. This integrated framework can be generalized to a large range of data-poor coastal and inland small-scale fisheries.

scholarly journals Métiers, effort and catches of a Mediterranean small-scale coastal fishery: the case of the gulf of Lion Marine Natural Parc

2020 ◽  
pp. 569-579
Author(s):  
Maxence Morel ◽  
Blandine Lapierre ◽  
Alice Goossens ◽  
Eva Dieudonné ◽  
Philippe Lenfant ◽  
...  
Keyword(s):  
Sparus Aurata ◽  
Fishing Effort ◽  
Western Mediterranean ◽  
Small Scale ◽  
Gilthead Seabream ◽  
Catch Per Unit Effort ◽  
Natural Park ◽  
Gulf Of Lion ◽  
Spatio Temporal ◽  
One Year

In the context of current fisheries crisis, this study aimed describing the characteristics of the artisanal fisheries in the Gulf of Lion Marine Natural Park located north-western Mediterranean. Catch Per Unit Effort and fishing effort were described on a spatio-temporal scale. Data were collected through questionnaires to fishers at landing sites for a one-year between 2019 and 2020. The most frequently used métiers were the hake gillnet and the sparids trammel net and gillnet, targeting two predominant species: hake (Merluccius merluccius) and gilthead seabream (Sparus aurata).

scholarly journals In the Wrong Place at the Wrong Time: Identifying Spatiotemporal Co-occurrence of Bycaught Common Dolphins and Fisheries in the Bay of Biscay (NE Atlantic) From 2010 to 2019

2021 ◽  
Vol 8 ◽  
Author(s):  
Helene Peltier ◽  
Matthieu Authier ◽  
Florence Caurant ◽  
Willy Dabin ◽  
Pierre Daniel ◽  
...  
Keyword(s):  
Atlantic Coast ◽  
Sea Bass ◽  
Fishing Effort ◽  
Small Scale ◽  
Common Dolphin ◽  
Bay Of Biscay ◽  
The European Union ◽  
Fishing Activity ◽  
Fishing Vessels ◽  
Common Dolphins

The first Unusual Mortality Event (UME) related to fishing activity along the Atlantic coast recorded by the French Stranding Network was in 1989: 697 small delphinids, mostly common dolphins, washed ashore, most of them with evidence of having been bycaught. Since then, UMEs of common dolphins have been observed nearly every year in the Bay of Biscay; unprecedented records were broken every year since 2016. The low and unequally distributed observation efforts aboard fishing vessels in the Bay of Biscay, as well as the lack of data on foreign fisheries necessitated the use of complementary data (such as stranding data) to elucidate the involvement of fisheries in dolphin bycatch. The aim of this work was to identify positive spatial and temporal correlations between the likely origins of bycaught stranded common dolphins (estimated from a mechanistic drift model) and fishing effort statistics inferred from Vessel Monitoring System (VMS) data on vessels >12 m long. Fisheries whose effort correlated positively with dolphin mortality areas after 2016 included French midwater trawlers, French Danish seiners, French gillnetters, French trammel netters, Spanish bottom trawlers, and Spanish gillnetters. For the French fleet only, logbook declarations, sales, and surveys carried out by Ifremer were integrated into fishing effort data. Six fleets were active in common dolphin bycatch areas at least twice between 2016 and 2019: gillnetters fishing hake, trammel netters fishing anglerfish, bottom pair trawlers fishing hake, midwater pair trawlers fishing sea bass and hake, and Danish seiners fishing whiting. Except for changes in hake landings in some fisheries, there were no notable changes in total fishing effort practice (gear or target species) based on the data required by the ICES and Council of the European Union that could explain the large increase in stranded common dolphins recorded along the French Atlantic coast after 2016. Small scale or unrecorded changes could have modified interactions between common dolphins and fisheries, but could not be detected through mandatory data-calls. The recent increase in strandings of bycaught common dolphins could have been caused by changes in their distribution and/or ecology, or changes in fishery practices that were undetectable through available data.

Short-term decisions of small-scale fishers selecting alternative target species: a choice model

2004 ◽  
Vol 61 (3) ◽  
pp. 374-383 ◽  
Author(s):  
Silvia Salas ◽  
Ussif Rashid Sumaila ◽  
Tony Pitcher
Keyword(s):  
Resource Availability ◽  
Choice Model ◽  
Daily Basis ◽  
Discrete Choice Models ◽  
Fishing Effort ◽  
Small Scale ◽  
Target Species ◽  
Catch Per Unit Effort ◽  
Small Scale Fisheries ◽  
Management Policies

The complexity of small-scale fisheries makes it difficult to predict the allocation of fishing effort among alternative target species in mixed fisheries, resulting in limitation for fisheries management. One reason for the difficulty is that fishing effort has been assumed as an aggregate of different components, without consideration of fishers' decisions. In this paper, we use discrete choice models to identify factors involved in fishers' decisions about selecting target species on a daily basis. We analyze catch data, by species and fisher, from three fishing communities of Yucatan, Mexico, to contrast the following models: (i) random selection, (ii) economic motivation, and (iii) changes in resource availability. Our results show that fishers do not operate at random but consider information on resource availability and revenues generated from previous trips before selecting or shifting a target. We compare the results among communities and also use the proposed models to predict changes in fishing effort levels given changes in species price and catch per unit effort. We stress the importance of understanding fishers' behavior when it comes to developing appropriate management policies.

Risk aversion in allocating fishing effort in a highly uncertain coastal fishery for pelagic fish, Moluccas, Indonesia

2001 ◽  
Vol 58 (8) ◽  
pp. 1683-1691 ◽  
Author(s):  
JAE van Oostenbrugge ◽  
WLT van Densen ◽  
M A.M Machiels
Keyword(s):  
Fold Increase ◽  
Fishing Effort ◽  
Pelagic Fish ◽  
Small Scale ◽  
Catch Per Unit Effort ◽  
Effort Allocation ◽  
Operation Costs ◽  
By Catch ◽  
Local Use ◽  
Very High

The Ambonese small-scale purse-seine fishery for small pelagic fish, such as scads and mackerels, is characterised by highly variable daily catches. Fishermen involved in this fishery are therefore seriously constrained in optimising the outcome of their fishery through spatial allocation of effort. Spatial patterns in effort allocation were compared with those in catch per unit effort (CPUE), indexed by both catch weight and profit. Average CPUE indexed by catch weight differed between fishing locations by up to 14 times. However, individual fishermen could only detect such large differences after 14 days of exploratory fishing because of the high variability in daily catches. Daily decisions on effort allocation are therefore not based on maximising CPUE but on minimising operational costs and risk. A very high proportion (88%) of the fishing trips were made within 8 km of the home port, although the capacity of the purse seiners allowed for fishing in more productive areas much farther away. A 10- to 20-fold increase in operation costs (travelling and local use rights) when fishing in other areas reinforced this behaviour.

scholarly journals Determinants of lungworm specificity in five cetacean species in the western Mediterranean

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Rachel Pool ◽  
Clara Romero-Rubira ◽  
Juan Antonio Raga ◽  
Mercedes Fernández ◽  
Francisco Javier Aznar
Keyword(s):  
Bottlenose Dolphins ◽  
Parasite Burden ◽  
Western Mediterranean ◽  
Host Size ◽  
Cetacean Species ◽  
Stenella Coeruleoalba ◽  
Species Similarity ◽  
Pilot Whales ◽  
Common Dolphins ◽  
Prey Overlap

Abstract Background Current data about Pseudaliidae show contrasting patterns of host specificity between congeneric species. We investigated how both contact and compatibility between hosts and parasites contributed to the patterns of lungworm infection observed in a community of five species of cetaceans in the western Mediterranean. Methods The lungs of 119 striped dolphins Stenella coeruleoalba, 18 bottlenose dolphins Tursiops truncatus, 7 Risso’s dolphins Grampus griseus, 7 long-finned pilot whales Globicephala melas, and 6 common dolphins Delphinus delphis were analysed for lungworms. Parasites were identified by morphology and analysis of ITS2 sequences using both maximum likelihood and Bayesian inference methods. Body length was used as a proxy for lungworm species fitness in different hosts and compared with Kruskal-Wallis tests. Infection parameters were compared between cetacean species using Fisher’s exact tests and Kruskal-Wallis tests. Phylogenetic specificity was explored by collating the overall lungworm species prevalence values in hosts from previous surveys in various localities. To explore the relative importance of vertical and horizontal transmission, Spearman’s rank correlation was used to look for an association between host size and lungworm burden. A Mantel test was used to explore the association between lungworm species similarity and prey overlap using dietary data. Results Halocercus delphini had higher infection levels in striped dolphins and common dolphins; Stenurus ovatus had higher infection levels in bottlenose dolphins; and Stenurus globicephalae had higher infection levels in long-finned pilot whales. These results are congruent with findings on a global scale. Morphometric comparison showed that the larger nematodes were found in the same host species that had the highest parasite burden. Lungworms were found in neonatal striped dolphins and a Risso’s dolphin, and there was a weak but significant correlation between host size and parasite burden in striped dolphins and bottlenose dolphins. There was also a weak but significant association between prey overlap and lungworm species similarity. Conclusions Data indicate that phylogenetic specificity has an important role in governing host–parasite associations, as indicated by the higher infection levels and larger nematode size in certain hosts. However, diet can also influence infection patterns in these preferred hosts and contribute to less severe infections in other hosts.

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