Fishing on floating objects (FOBs): how French tropical tuna purse seiners split fishing effort between GPS-monitored and unmonitored FOBs

2018 ◽  
Vol 75 (11) ◽  
pp. 1849-1858 ◽  
Author(s):  
Julia E. Snouck-Hurgronje ◽  
David M. Kaplan ◽  
Emmanuel Chassot ◽  
Alexandra Maufroy ◽  
Daniel Gaertner
Keyword(s):  
Search Time ◽  
Fishing Effort ◽  
Purse Seine ◽  
Trajectory Data ◽  
Catch Per Unit Effort ◽  
Position Information ◽  
Foreign Objects ◽  
Tropical Tuna ◽  
Floating Objects ◽  
Over Time

Fishing on floating objects (FOBs) dominates catch in tropical tuna purse seine fisheries. One frequently cited advantage of deploying GPS-monitored FOBs is that the position information can be used for directed fishing to reduce search time for tuna. However, purse seiners also fish on foreign objects for which position information is not available. It is critical to quantify the prevalence of fishing on GPS-monitored versus unmonitored FOBs to understand how they impact fishing effort and catch per unit effort. We analyzed French commercial, observer, and FOB trajectory data in the Atlantic and Indian oceans to determine how often purse seine vessels fish on GPS-monitored FOBs. Only 2.7%–20.4% of French FOB fishing sets over 2007–2013 in both oceans were made on GPS-monitored FOBs. Though increasing over time, the low percentage suggests that French vessels do not primarily use GPS-monitored FOBs to reduce search time for tuna. We hypothesize that fishery-wide FOB deployments have important collective consequences for overall fishing effort and recommend that future effort metrics should be based on fishery-wide FOB activities.

scholarly journals Quantifying the increase in fishing efficiency due to the use of drifting FADs equipped with echosounders in tropical tuna purse seine fisheries

2020 ◽  
Author(s):  
Gwenaëlle Wain ◽  
Loreleï Guéry ◽  
David Michael Kaplan ◽  
Daniel Gaertner
Keyword(s):  
New Technology ◽  
Recent Change ◽  
Purse Seine ◽  
Catch Per Unit Effort ◽  
Katsuwonus Pelamis ◽  
Thunnus Obesus ◽  
Efficiency Increase ◽  
Tropical Tuna ◽  
Floating Objects ◽  
The Impact

Abstract Numerous pelagic species are known to associate with floating objects (FOBs), including tropical tunas. Purse seiners use this behaviour to facilitate the capture of tropical tunas by deploying artificial drifting fish aggregating devices (dFADs). One major recent change has been the integration of echosounders in satellite-tracked GPS buoys attached to FOBs, allowing fishers to remotely estimate fishable biomass. Understanding the effects of this new technology on catch of the three main tuna species (yellowfin tuna, Thunnus albacares; bigeye tuna, Thunnus obesus; and skipjack tuna, Katsuwonus pelamis) is important to accurately correct for this change in catch-per-unit-effort (CPUE) indices used for stock assessments. We analysed catch data from the French purse seine fleet for the period 2010–2017 in the Indian Ocean to assess the impact of this fleet’s switch to echosounder buoys around 2012. Results indicate that echosounders do not increase the probability a set will be succesful, but they have a positive effect on catch per set, with catches on average increasing by ≈2−2.5 tonnes per set (≈10%) when made on the vessel's own dFADs equipped with an echosounder buoy. Increases were due to a decrease in sets below ≈25 tonnes and an increase in those greater than ≈25 tonnes, with a non-linear transition around this threshold. This increase explains the considerable investment of purse seiners in echosounder buoys, but also raises concerns about bias in stock size estimates based on CPUE if we do not correct for this fishing efficiency increase.

scholarly journals RESPONSIBLE FISHERIES MANAGEMENT OF MINI PURSE SEINE IN THE LAMPUNG BAY AREA

2017 ◽  
Vol 8 (2) ◽  
pp. 713-728
Author(s):  
Yulia Estmirar Tanjov ◽  
Roza Yusfiandayani ◽  
. Mustaruddin
Keyword(s):  
Fishing Effort ◽  
Maximum Sustainable Yield ◽  
Pelagic Fish ◽  
Purse Seine ◽  
Sustainable Yield ◽  
Catch Per Unit Effort ◽  
Small Pelagic Fish ◽  
Bay Area ◽  
Fisheries Resources ◽  
The Status

Lempasing is a Coastal Fishing Port (CFP) which located in Bandar Lampung. It is one of the centers of fisheries activities in the city. One of the fishing gear which operated by most of fishermen in Lempasing is mini purse seine. Mini purse seine fishing activities in the Lampung Bay Area and Lempasing CFP is not in accordance with the conditions of the surrounding waters area. The research was conducted in the Lampung Bay Area and Lempasing CFP, Lampung. This study aims to: 1) determine the status of fisheries resources utilization, 2) to describe the dominant fish caught by mini purse seine.  Analysis methods were used in this study namely: 1) Fishing Power Index (FPI), Catch Per Unit Effort (CPUE), and Maximum Sustainable Yield (MSY) to determine the status of fisheries resource utilization. The dominant small pelagic fishes caught were scad fish Selaroides sp., mackerel fish Rastrelliger sp., longnose trevally fish Carangoides chrysophrys. The result showed that Fox model was the best fits models with estimated maximum sustainable yield of 15.5 ton and fishing effort of 992 trip/year for mini purse seine. The longnose trevally fish in lampung bay area in do not exceeded the optimal catch fish condition can be used to sustainably. In these condition is necessary to wisely manage and setting the catches to not exceed the allowable catch of the small pelagic fish, so the stock of small pelagic fish in the Lampung Bay Area can be used sustainably.

scholarly journals RESPONSIBLE FISHERIES MANAGEMENT OF MINI PURSE SEINE IN THE LAMPUNG BAY AREA

2017 ◽  
Vol 8 (2) ◽  
pp. 713
Author(s):  
Yulia Estmirar Tanjov ◽  
Roza Yusfiandayani ◽  
. Mustaruddin
Keyword(s):  
Fishing Effort ◽  
Maximum Sustainable Yield ◽  
Pelagic Fish ◽  
Purse Seine ◽  
Sustainable Yield ◽  
Catch Per Unit Effort ◽  
Small Pelagic Fish ◽  
Bay Area ◽  
Fisheries Resources ◽  
The Status

<p><em>Lempasing is a Coastal Fishing Port (CFP) which located in Bandar Lampung. It is one of the centers of fisheries activities in the city. One of the fishing gear which operated by most of fishermen in Lempasing is mini purse seine. Mini purse seine fishing activities in the Lampung Bay Area and Lempasing CFP is not in accordance with the conditions of the surrounding waters area. The research was conducted in the Lampung Bay Area and Lempasing CFP, Lampung. This study aims to: 1) determine the status of fisheries resources utilization, 2)</em><em> to describe the dominant fish caught by mini purse seine. </em><em> Analysis methods were used in this study namely: 1) Fishing Power Index (FPI), Catch Per Unit Effort (CPUE), and Maximum Sustainable Yield (MSY) to determine the status of fisheries resource utilization. The dominant small pelagic fishes caught were scad fish <span style="text-decoration: underline;">Selaroides</span> </em>sp<em>., mackerel fish <span style="text-decoration: underline;">Rastrelliger</span> </em>sp<em>., longnose trevally fish <span style="text-decoration: underline;">Carangoides</span> <span style="text-decoration: underline;">chrysophrys</span>. The result showed that Fox model was the best fits models with estimated maximum sustainable yield of 15.5 ton and fishing effort of 992 trip/year for mini purse seine. The longnose trevally fish in lampung bay area in do not exceeded the optimal catch fish condition can be used to sustainably. In these condition is necessary to wisely manage and setting the catches to not exceed the allowable catch of the small pelagic fish, so the stock of small pelagic fish in the Lampung Bay Area can be used sustainably.</em></p>

Inverse regional responses to climate change and fishing intensity by the recreational rockfish (Sebastes spp.) fishery in California

2004 ◽  
Vol 61 (12) ◽  
pp. 2499-2510 ◽  
Author(s):  
William A Bennett ◽  
Kimy Roinestad ◽  
Laura Rogers-Bennett ◽  
Les Kaufman ◽  
Deb Wilson-Vandenberg ◽  
...  
Keyword(s):  
Principal Component ◽  
Fishing Effort ◽  
Interactive Effects ◽  
Catch Per Unit Effort ◽  
The South ◽  
Annual Fish ◽  
Ocean Climate ◽  
The North ◽  
Regional Responses ◽  
Over Time

The interactive effects of ocean climate and fishing pressure on nearshore rockfishes (Sebastes spp.) were examined using historical commercial passenger fishing vessel catch records from California. Principal component analysis was used to characterize the dominant patterns in catch per unit effort (CPUE) over time (1957–1999) and space (10′ latitude × 10′ longitude blocks). Ocean climate explained 60% of the variation in CPUE and revealed opposite responses in northern and southern California. In warm El Niño years, CPUE was 4.2 times higher in the north and 1.8 times lower in the south. CPUE responded similarly to low-frequency climate shifts by increasing in the north and decreasing in the south after 1976–1977. Four geographic regions responded as discrete units to environmental forcing and fishing intensity: North, Central, South, and Channel Islands. Over time, annual fish landings declined sharply in the South, with fishing effort remaining stationary and high relative to that in the other regions. In the North, landings and fishing effort remained tightly coupled, with effort an order of magnitude lower than in the South. These findings support a management strategy for nearshore rockfishes in California based on regional responses to ocean climate and fishing intensity.

Massive increase in the use of drifting Fish Aggregating Devices (dFADs) by tropical tuna purse seine fisheries in the Atlantic and Indian oceans

2016 ◽  
Vol 74 (1) ◽  
pp. 215-225 ◽  
Author(s):  
Alexandra Maufroy ◽  
David M. Kaplan ◽  
Nicolas Bez ◽  
Alicia Delgado De Molina ◽  
Hilario Murua ◽  
...  
Keyword(s):  
Relative Proportion ◽  
Major Change ◽  
Purse Seine ◽  
Fourfold Increase ◽  
Natural Objects ◽  
The Indian Ocean ◽  
Tropical Tuna ◽  
Floating Objects ◽  
Fish Aggregating Devices ◽  
Logbook Data

Since the mid-1990s, drifting Fish Aggregating Devices (dFADs), artificial floating objects designed to aggregate fish, have become an important mean by which purse seine fleets catch tropical tunas. Mass deployment of dFADs, as well as the massive use of GPS buoys to track dFADs and natural floating objects, has raised serious concerns for the state of tropical tuna stocks and ecosystem functioning. Here, we combine tracks from a large proportion of the French GPS buoys from the Indian and Atlantic oceans with data from observers aboard French and Spanish purse seiners and French logbook data to estimate the total number of dFADs and GPS buoys used within the main fishing grounds of these two oceans over the period 2007–2013. In the Atlantic Ocean, the total number of dFADs increased from 1175 dFADs active in January 2007 to 8575 dFADs in August 2013. In the Indian Ocean, this number increased from 2250 dFADs in October 2007 to 10 300 dFADs in September 2013. In both oceans, at least a fourfold increase in the number of dFADs was observed over the 7-year study period. Though the relative proportion of natural to artificial floating objects varied over space, with some areas such as the Mozambique Channel and areas adjacent to the mouths of the Niger and Congo rivers being characterized by a relatively high percentage of natural objects, in no region do dFADs represent &lt;50% of the floating objects and the proportion of natural objects has dropped over time as dFAD deployments have increased. Globally, this increased dFAD use represents a major change to the pelagic ecosystem that needs to be closely followed in order to assess its impacts and avoid negative ecosystem consequences.

Fishing activity of tuna purse seiners estimated from vessel monitoring system (VMS) data

2011 ◽  
Vol 68 (11) ◽  
pp. 1998-2010 ◽  
Author(s):  
Nicolas Bez ◽  
Emily Walker ◽  
Daniel Gaertner ◽  
Jacques Rivoirard ◽  
Philippe Gaspar
Keyword(s):  
Monitoring System ◽  
Spatial Organization ◽  
Compositional Data ◽  
State Space Model ◽  
Fishing Effort ◽  
Purse Seine ◽  
Seasonal Effect ◽  
Fishing Activity ◽  
Definition Of ◽  
Tropical Tuna

In the lack of fishery-independent information, catch per unit of effort (CPUE) is the conventional abundance index. In the case of the tropical tuna purse seine fisheries, a critical difficulty lies in the definition of an effective fishing effort, because fishermen use two different fishing modes (free swimming schools versus schools under fish aggregating devices) alternatively during the same trip. In this study, vessel monitoring system (VMS) data were used in an operational level to study and quantify the spatial dynamic of the tropical tuna purse seine fishing activity. A Bayesian state–space model allowed classifying VMS steps into three activities (fishing, tracking, and cruising), which were characterized by a small set of complementary spatial indicators. The dominant activity (49%) was clearly the tracking of tuna schools within areas of aggregations. A hierarchical spatial organization of the three fishing activities was also evidenced. Fishing strategies described by the triplets of proportions of time devoted to each activity and interpreted as compositional data were modelled by the sum of a vessel effect and a seasonal effect.

Comparison of Two Methods of Combining Catch-Per-Unit-Effort Data from Geographic Regions

1982 ◽  
Vol 39 (6) ◽  
pp. 837-846 ◽  
Author(s):  
Terrance J. Quinn II ◽  
Stephen H. Hoag ◽  
G. Morris Southward
Keyword(s):  
Variance Estimation ◽  
Fishing Effort ◽  
Data Sampling ◽  
Catch Per Unit Effort ◽  
Pacific Halibut ◽  
Unit Effort ◽  
Combining Data ◽  
Geographic Regions ◽  
Substantial Bias ◽  
Over Time

We examined two methods of combining catch-and-effort data from small geographic regions into large regulatory areas to estimate catch-per-unit-effort (CPUE): (1) weighting regional CPUE by bottom area occupied by the population; (2) weighting by fishing effort. Variance estimates and other statistical properties are presented for CPUE estimates by region and for the two methods, for the type of fishery where total catch is known. The CPUE estimator from area-weighting is approximately unbiased as an index of population density; the CPUE estimator from effort-weighting is biased but less variable than the former. Conditions of similarity are derived for estimators from the two methods to be identical, or, less restrictively, to show the same trend over time. In general, the area-weighted method is preferred, if sufficient samples are taken from all pertinent regions in the regulatory area. However, the effort-weighted method may be used with a gain in precision and no substantial bias, if there are no substantial changes in relative CPUE and effort among regions, or if relative CPUE and effort are inversely related. The two methods applied to catch and effort data for Pacific halibut (Hippoglossus stenolepis) and to produce highly similar CPUE estimates over time, despite large relative changes in both CPUE and effort among regions. The reasons for the similarity are traced back to conditions in the fishery.Key words: catch-per-unit-effort, combining data, sampling commercial fisheries, variance estimation, comparison of methods

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.

Population Dynamics of the Arcto-Norwegian Cod

1967 ◽  
Vol 24 (1) ◽  
pp. 145-190 ◽  
Author(s):  
D. J. Garrod
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Fishing Effort ◽  
Catch Per Unit Effort ◽  
Group Iii ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
Post War ◽  
The One ◽  
Definition Of

By reason of its geographical distribution, the Arcto-Norwegian cod (Gadus morhua) supports three distinct fisheries, two feeding fisheries in the Barents Sea and at Bear Island–Spitsbergen, and a spawning fishery off the Norway coast. In the past this diversity of fishing on the one stock has made it difficult to unify all the data to give an overall description of post-war changes in the stock. In this contribution three modifications of conventional procedures are introduced which enable this to be done. These are: (i) a system of weighting the catch per unit effort data from each fishery to a level of comparability; (ii) a more rigorous definition of the effective fishing effort on each age-group; (iii) a method of estimation of the effective fishing effort on partially recruited age-groups.Using these methods the analysis presents the effects of fishing on each fishery in the context of its effect on the total stock, and at the same time it indicates ways in which factors other than fishing may have influenced the apparent abundance of the stock. The treatment of the data is also used to derive estimates of spawning stock and recruitment of 3-year-old cod for subsequent analysis of stock–recruitment relationships.

Implications of interference among fishing vessels and the ideal free distribution to the interpretation of CPUE

1998 ◽  
Vol 55 (1) ◽  
pp. 37-46 ◽  
Author(s):  
D M Gillis ◽  
R M Peterman
Keyword(s):  
Ideal Free Distribution ◽  
Fishing Effort ◽  
Catch Per Unit Effort ◽  
Free Distribution ◽  
Fishing Vessels ◽  
Factor Interactions ◽  
The Relationship ◽  
Index Of Abundance ◽  
Ideal Free ◽  
The Ideal

Despite recognized biases, catch per unit effort (CPUE) statistics remain widely used for the estimation of fish abundance. Previous workers have shown that CPUE can be a misleading index of abundance due to fish behavior, the nominal effort units used, and increases through time in efficiency of fishing (catchability). We examine the theoretical implications of a different factor, interactions among fishing vessels, for the relationship between abundance and CPUE. Our model simulates a fishery that occurs in several adjacent fishing grounds. The spatial distribution of catch and effort is based on a simplification of the Baranov catch equation, the relationship between fishing efficiency and local fishing effort (interference), and the assumptions of the ideal free distribution. Our results indicate that (i) even low levels of interference among fishing vessels can cause a breakdown in the correlation between CPUE and local abundance and (ii) the influence of interference on this relationship is dependent on the correlation of abundances among adjacent areas. Our model suggests an alternative index of abundance, based on the proportion of fishing effort on a ground, that would be appropriate for cases where interference occurs among fishing gear.

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