Can vessel monitoring system data also be used to study trawling intensity and population depletion? The example of Australia's northern prawn fishery

2005 ◽  
Vol 62 (3) ◽  
pp. 611-622 ◽  
Author(s):  
Roy Deng ◽  
Cathy Dichmont ◽  
David Milton ◽  
Mick Haywood ◽  
David Vance ◽  
...  
Keyword(s):  
Monitoring System ◽  
Fishing Effort ◽  
Catch Per Unit Effort ◽  
Fishing Vessels ◽  
Tiger Prawn ◽  
System Data ◽  
Stock Depletion ◽  
Using Data ◽  
The Impact ◽  
Northern Prawn Fishery

We explore the potential of using data from Australia's northern prawn fishery (NPF) vessel monitoring system(s) (VMS) to examine trawl track, trawling intensity, and stock depletion due to trawling. We simulate VMS data by subsampling global positioning system (GPS) fixes from the NPF fishing vessels at different polling intervals to examine their accuracy in describing trawl tracks. The results of the simulations suggest that VMS data with polling intervals longer than 30 min cannot accurately estimate trawl tracks. The analysis of high-polling-frequency VMS data collected in four (later reduced to three) 6 nautical mile × 6 nautical mile grids that historically received high levels of fishing effort showed that trawling was not random and some areas were trawled up to 28 times in the tiger prawn fishing season and the impact varied among years. The results of a catch-depletion analysis suggest that fishery catch-per-unit-effort and cumulative catch may not be proportional to overall target-species biomass in areas with highly aggregated trawl effort. The VMS data also showed a large number of trawls can occur in productive areas and that trawling impacts on benthos may be quite marked.

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.

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.

Movement Dynamics in a Fishery: Application of the Ideal Free Distribution to Spatial Allocation of Effort

1993 ◽  
Vol 50 (2) ◽  
pp. 323-333 ◽  
Author(s):  
Darren M. Gillis ◽  
Randall M. Peterman ◽  
Albert V. Tyler
Keyword(s):  
Spatial Distribution ◽  
Ideal Free Distribution ◽  
Fishing Effort ◽  
Catch Per Unit Effort ◽  
Exploitation Competition ◽  
Spatial Allocation ◽  
Free Distribution ◽  
Fishing Vessels ◽  
Ideal Free ◽  
The Ideal

Many traditional analyses of fisheries data assume that there is a negligible effect of alternative fish stocks on the spatial distribution of fishing effort and that the amount of local effort does not influence catchability. There is growing evidence that contradicts these assumptions. Because of the potential biases that these erroneous assumptions may cause in the interpretation of catch-per-unit-effort (CPUE) statistics, it is important to determine the factors governing the spatial distribution of effort in a fishery. We used data on the Hecate Strait, British Columbia, Canada, trawl fishery to test hypotheses about spatial allocation of effort and interaction among fishing vessels. The ideal free distribution of Fretwell and Lucas (1970. Acta Biotheor. 19: 16–36) was the foundation for deriving these tests. We found evidence for competition among vessels, although we could not distinguish whether the mechanism was interference or exploitation competition. As well, CPUE was generally equalized among the areas fished, as predicted by the ideal free distribution, because of movement of boats among areas. Thus, area-specific CPUE would not be a reliable index of relative abundance of fish in different areas; relative fishing effort may be better.

scholarly journals Indirect Impacts of COVID-19 on a Tropical Lobster Fishery’s Harvest Strategy and Supply Chain

2021 ◽  
Vol 8 ◽  
Author(s):  
Éva Plagányi ◽  
Roy Aijun Deng ◽  
Mark Tonks ◽  
Nicole Murphy ◽  
Sean Pascoe ◽  
...  
Keyword(s):  
Supply Chain ◽  
Fishing Effort ◽  
Weak Links ◽  
Catch Per Unit Effort ◽  
Critical Data ◽  
Global Pandemic ◽  
Harvest Control Rule ◽  
Harvest Strategy ◽  
Indirect Impacts ◽  
The Impact

The Torres Strait tropical rock lobster Panulirus ornatus (TRL) fishery is of immense social, cultural and economic importance to the region’s Indigenous fishers from both Australia and Papua New Guinea (PNG). During 2020, the COVID-19 pandemic indirectly impacted this fishery as well as a number of other fisheries reliant on international export markets. The TRL fishery is managed using an empirical (data-based) Harvest Control Rule (eHCR) to rapidly provide a recommended biological catch (RBC), based on catch, fishery-independent survey indices and catch-per-unit-effort (CPUE). Here, we summarize the impacts of COVID-19 on each of these critical data inputs and discuss whether the eHCR was considered adequately resilient to this unprecedented disruption to the system. Next, we use a quantitative supply chain index to analyze the impact of disruptions to the supply chain, and inform on potential adaptation strategies. The catch and CPUE data were impacted to varying degrees by external constraints influencing fishing effort, but the fishery-independent survey wasn’t affected and hence there remains an unbroken survey time-series for the fishery extending back to 1989. The eHCR was shown to be reasonably robust because it incorporates longer-term trends over a 5-year period, and accords substantially more weighting (80%) to the fishery-independent survey rather than CPUE data which can be affected by trade and other disruptions. Despite the eHCR not having been tested for scenarios such as a global pandemic, this robustness is a positive given the types of disruptions we will likely face in future climate. The weak links identified in the supply chain were the same as those previously highlighted as sensitive to climate change disruptions. Our supply chain analysis quantifies the impact on system resilience of alternative paths connecting producers to consumers and reinforces that supply chains may be particularly vulnerable to external disruptions if they are not sufficiently diverse.

scholarly journals Effect of hook and bait type on catch per unit effort in the Aegean Sea demersal longline fishery

2021 ◽  
Vol 38 (2) ◽  
pp. 181-188
Author(s):  
Ozan Soykan ◽  
Cemil Sağlam ◽  
İlker Aydın ◽  
Hasan Tuncay Kınacıgil
Keyword(s):  
Sparus Aurata ◽  
Length Distribution ◽  
Aegean Sea ◽  
Fishing Effort ◽  
Longline Fishery ◽  
Total Catch ◽  
Catch Per Unit Effort ◽  
Unit Effort ◽  
Catch Composition ◽  
The Impact

This study aimed to determine the impact of hook and bait type on the catch composition and catch per unit effort. Effects of hook and bait types on catch composition, catch per unit effort (CPUE), length and weight distributions in demersal longline fishery were determined by experimental surveys on demersal longline sets in the Aegean Sea. A total of 12 samplings corresponding to 4800 hook fishing effort were performed between April 2014 and September 2014. Two bait types; sardine (Sardina pilchardus) and grooved razor shell (Solen marginatus) and two hook types; J-hook and C-hook were tested. CPUE values were calculated for each species and assessed between different hook-bait combinations. A total of 623 individuals were captured belonging to 3 families and 9 species. It was found that more than 60% of total catch was captured by grooved razor shell and more than 50% of the total catch was caught with J type hook. J hook was found to be close to significant (p=0.06) and grooved razor shell was found significant (p=0.02) for CPUE. The effect of bait type was found to be more significant than that of hook type for CPUE and length distribution. Hook-bait combination differed according to species and C hook baited with sardine was determined to be the best combination for Sparus aurata as the most targeted fish in the study area. Discard ratio was calculated to be 34% in terms of weight and 42.5% in terms of total number of individuals for pooled data. The condition value (K) of the species ranged from 1.05 to 1.68 and differed according to bait type. Most of the high commercial value species caught with any hook-bait combination experimented within this study are larger than minimum fishing length according to minimum landing size regulations of Turkish fishery and maturity studies.

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.

Managing Scarce Resources and Sensitive Ecosystems: Assessing the Role of CFP in the Development of Portuguese Fisheries

2016 ◽  
Vol 18 (04) ◽  
pp. 1650022 ◽  
Author(s):  
Pedro Valadas Monteiro
Keyword(s):  
Fishing Effort ◽  
Scarce Resources ◽  
Fishing Vessels ◽  
The Social ◽  
Wide Range ◽  
Fisheries Policy ◽  
Regulatory Instruments ◽  
Annual Total ◽  
Using Data

The aim of this paper is to assess the main impacts of the Common Fisheries Policy (CFP) in the development of Portuguese fisheries. CFP has introduced a wide range of regulatory instruments, such as the annual total allowable catches (TACs), restrictions on the permissible number of fishing days, fleet reductions and limits on the size and engine power of fishing vessels, alongside with some technical measures to regulate gear usage and where and when fishermen can fish. We analyse the trend evidenced by some of the most relevant structural dimensions of the Portuguese fishing fleet using data surveyed from the Statistics Portugal database for a 21 year period (1994–2014). The results suggest that CFP, namely its conservation measures, has failed so far to achieve its fundamental objective of matching fishing effort and living resources through the coupling of biologic objectives with the ones related to the social and economic aspects of fisheries.

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