Results of a short study of interactions of cetaceans and longline fisheries in Atlantic waters: environmental correlates of catches and depredation events

Hernández-Milian, Gema; Goetz, Sabine; Varela‐Dopico, Catuxa; Rodriguez-Gutierrez, José; Romón-Olea, Jorge; Fuertes-Gamundi, José R.; Ulloa-Alonso, Edelmiro; Tregenza, Nick; Smerdon, Andy; Otero, Monserrat G.; Tato, V.; Wang, Jianjun; Santos, M. Begoña; López, Alfredo; Lago, Rebeca; Portela, J.; Pierce, Graham J.

doi:10.1007/s10750-008-9501-2

Cited by 38 publications

(21 citation statements)

References 28 publications

(29 reference statements)

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“…These results are similar to those of Hernandez‐Milian et al. (), who reported occurrences of depredation in the Atlantic Ocean were <1% of the total catch. Rabearisoa, Sabarros et al.…”

Section: Discussionsupporting

confidence: 91%

“…By contrast, IR was higher compared with other studies, such as Hernandez‐Milian et al. () in the Atlantic Ocean and Rabearisoa, Sabarros et al. () in the Indian Ocean.…”

Section: Discussioncontrasting

confidence: 69%

“…For swordfish, the effects of the spatial variables (latitude and longitude) were significant on the rate of depredation events both in the Atlantic and Indian oceans. It is possible that variables such as temperature or depth, related to spatial variables, are related to the distribution of the catches of oceanic migratory species (Hernandez‐Milian et al., ), which in turn can lead to more depredation. GAM models predict the probability of having or not having predation events, but the most likely responsible species in each region was not explored because of the limits in the analysis and specifically in the taxa‐specific data availability.…”

Section: Discussionmentioning

confidence: 99%

“…However, detailed information collected systematically is still rare for both areas. Therefore, there is a need for the development of specific indicators to assess the degree of depredation, especially in poorly studied areas of the Indian (Mutombene, ; Rabearisoa, Sabarros, Romanov, & Bach, ; Varghese, Somvanshi & Varghese, ) and Atlantic Oceans (Hernandez‐Milian et al., ; MacNeil, Carlson & Beerkircher, ; Mandelman, Cooper, Werner & Lagueux, ).…”

Section: Introductionmentioning

confidence: 99%

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Depredation in pelagic surface longlines in the Atlantic and Indian Oceans

Muñoz‐Lechuga

Coelho

2018

Fisheries Management Eco

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Depredation has aroused great interest over the last few decades, mainly due to the expansion of distant fishing, in particular longlines. For this study, captures and depredation records were taken by scientific observers on board Portuguese commercial longline vessels in the Atlantic and Indian Oceans between 2011 and 2016. A total of 1,336 fishing sets were monitored, with a total of 86,183 fish captured, including 1,681 depredation events. The percentage of depredation tended to increase along the time series, except in the last year where a decrease was noted. Significant differences between sizes of swordfish Xiphias gladius damaged by predators were observed in the Indian Ocean but not in the Atlantic. The highest proportions of depredation were observed on tuna and small pelagic fishes in both oceans. For swordfish, the effects of spatial variables were significant on the rate of depredation events. The results provide an overview of the depredation patterns in the Portuguese pelagic longline fishery in the Atlantic and Indian Oceans, which can inform and improve fisheries management and contribute to the development of effective mitigation measures to reduce the impacts of depredation on fisheries.

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“…These results are similar to those of Hernandez‐Milian et al. (), who reported occurrences of depredation in the Atlantic Ocean were <1% of the total catch. Rabearisoa, Sabarros et al.…”

Section: Discussionsupporting

confidence: 91%

“…By contrast, IR was higher compared with other studies, such as Hernandez‐Milian et al. () in the Atlantic Ocean and Rabearisoa, Sabarros et al. () in the Indian Ocean.…”

Section: Discussioncontrasting

confidence: 69%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Depredation in pelagic surface longlines in the Atlantic and Indian Oceans

Muñoz‐Lechuga

Coelho

2018

Fisheries Management Eco

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“…Conversely, Podestá et al (1993), similarly to the presently reported study, could not demonstrate significant correlation between CPUE and lunar illumination. Furthermore, Hernandez-Milian et al (2008) reported weakly significant relations between swordfish catches and both cloud cover, as well as the interaction between lunar phase and cloud cover. In the swordfish gillnet fishery operating in the central Mediterranean Sea, Di showed that the lowest catch rates were occurring during the full Moon.…”

Section: Discussionmentioning

confidence: 96%

The effect of the lunar phase on the catch per unit effort (CPUE) of the Turkish swordfish longline fishery in the eastern Mediterranean Sea

Ceyhan¹,

Tserpes²,

Akyol³

et al. 2018

Acta Ichthyol. Piscat.

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Background. The swordfish, Xiphias gladius Linnaeus, 1758, is a pelagic and highly migratory species distributed in the Atlantic, Indian, and Pacific oceans as well as in the Mediterranean Sea. Swordfish fishing has been carried out in the Mediterranean with longlines, gillnets, harpoons, and traps since the Roman times. Although information is available on the influence of the lunar phase on the catch per unit effort (CPUE) for the swordfish longline fishery in the Atlantic and Pacific oceans, the data concerning the Mediterranean is rather limited. The aim of this study was to examine the relation between the lunar phase and the swordfish CPUE, based on data from Turkish longline fisheries, targeting swordfish in the eastern Mediterranean during the 2008-2016 fishing seasons. Material and methods. We monitored randomly the daily fishing activity of longliners based at the ports of Fethiye and Özdere during 2008-2016. A total of 86 surveying operations were carried out, including 79 in the area between Fethiye and Alanya, the remaining ones were in Özdere in the southern Aegean coasts along the eastern Mediterranean Sea. The effect of the lunar phase on the swordfish catch rates, expressed in terms of kg • 1000 hooks-1 , was examined by means of the Generalized Additive Modelling (GAMs) techniques. Results. The observed CPUE rates ranged from 0 to 700 kg • 1000 hooks-1. The mean swordfish CPUEs in the dark and light periods of the lunar cycle were equal to 178.10 ± 19.01 and 175.27 ± 19.56 kg • 1000 hooks-1 , respectively. Although no significant differences among phases of the Moon were found (P > 0.05), CPUEs differed significantly between years (P < 0.05). Conclusion. It seems that the mechanism linking swordfish CPUE variations with the lunar cycle involves several factors, making difficult the identification of direct relations. Further studies are needed to better clarify the impact of the lunar phase on the longline gear, considering also additional parameters, such as light transition, prey abundance, physico-chemical characteristics of the marine environment, and the soak time of the gear.

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A review of interactions between cetaceans and fisheries in the Azores

Silva

Machete

Reis

et al. 2010

Aquatic Conservation

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ABSTRACT1. Interactions between cetaceans and fishing activity in the Archipelago of the Azores were examined using information contained in grey literature and previously unpublished data collected by observer programmes and research projects from 1998 to 2006. Together with a brief description of the economics, gear, fishing effort, and past and ongoing monitoring projects, levels of cetacean bycatch and interference were reported for each major fishery.2. Cetaceans were present in 7% (n=973) and interfered in 3% (n=452) of the fishing events monitored by observers aboard tuna-fishing vessels. Interference resulted in a significantly higher proportion of events with zero catches but it was also associated with higher tuna catches. 4. Observers reported cetacean depredation in 16% of the sets for demersal species and in 2% of the sets for swordfish. Cetacean presence and depredation were associated with higher overall catches and higher catches per unit effort in demersal fisheries.Bottlenose dolphins (Tursiops truncatus) were responsible for most depredation events in demersal fisheries, whereas in the swordfish fishery, depredation was associated with the presence of killer whales (Orcinus orca). There were no reports of cetacean bycatch in these fisheries. There were also no reports of cetaceans interacting in the experimental deep-sea fisheries that were examined.5. Available data suggests that levels of interaction between cetaceans and Azorean fisheries are generally low and that the economic impact of cetacean interference is probably small. However, for several traditional fisheries there are no accurate data to determine levels of cetacean interaction. We recommend that existing observer programmes be expanded to increase observer coverage of the demersal and swordfish fisheries and allow monitoring of other existing and emerging fisheries.

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Results of a short study of interactions of cetaceans and longline fisheries in Atlantic waters: environmental correlates of catches and depredation events

Cited by 38 publications

References 28 publications

Depredation in pelagic surface longlines in the Atlantic and Indian Oceans

Depredation in pelagic surface longlines in the Atlantic and Indian Oceans

The effect of the lunar phase on the catch per unit effort (CPUE) of the Turkish swordfish longline fishery in the eastern Mediterranean Sea

A review of interactions between cetaceans and fisheries in the Azores

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