scholarly journals Developing and evaluating harvest control rules with different biological reference points for the American lobster (Homarus americanus) fishery in the Gulf of Maine

2011 ◽  
Vol 68 (7) ◽  
pp. 1511-1524 ◽  
Author(s):  
Yuying Zhang ◽  
Yong Chen ◽  
Carl Wilson
Keyword(s):  
Gulf Of Maine ◽  
Homarus Americanus ◽  
The United States ◽  
Reference Points ◽  
Systematic Evaluation ◽  
American Lobster ◽  
Natural Mortality ◽  
Control Rules ◽  
The Status ◽  
Harvest Control Rules

Abstract Zhang, Y., Chen, Y., and Wilson, C. 2011. Developing and evaluating harvest control rules with different biological reference points for the American lobster (Homarus americanus) fishery in the Gulf of Maine. – ICES Journal of Marine Science, 68: 1511–1524. The American lobster (Homarus americanus) supports one of the most valuable commercial fisheries in the United States. Controversy exists, however, in terms of the biological reference point (BRP) used in assessing lobster stock status, and there is no fully established or evaluated harvest control rule (HCR). A sex-specific, size-dependent operating model is developed to evaluate the performance of two HCRs, discrete and continuous, which adjust annual fishing mortality discretely and linearly, respectively, based on the status of the fishery. For each HCR, different BRPs are considered along with management duration, recruitment dynamics, and natural mortality. HCRs with a suitable set of BRPs can drive the fishery from an undesirable status to an optimal status. The continuous HCR tends to perform better than the discrete one. The Ftarget of 0.31 year−1 showed the best performance in the long term by balancing the needs of the fishing industry and conservation bodies. However, this was not the case in the short term. An Ntarget of 49.6 million would allow the American lobster to be maintained at its current stock level, with high recruitment and stable natural mortality. The study provides a framework for a systematic evaluation of management regulations for the American lobster.

A simulation study to evaluate impacts of uncertainty on the assessment of American lobster fishery in the Gulf of Maine

2002 ◽  
Vol 59 (8) ◽  
pp. 1394-1403 ◽  
Author(s):  
Yong Chen ◽  
Carl Wilson
Keyword(s):  
Confidence Level ◽  
Gulf Of Maine ◽  
Homarus Americanus ◽  
American Lobster ◽  
Large Uncertainty ◽  
Decision Confidence ◽  
The Status ◽  
Status Assessment ◽  
Lobster Fishery ◽  
Risk Managers

The status of the American lobster (Homarus americanus) in the Gulf of Maine (GOM) has been assessed for the last two decades by comparing an estimated current fishing mortality rate for females (Fcur) with a deterministically estimated biological reference point, F10%. The most recent assessment determined that GOM had exceeded the F10% for every year calculated, although in this time landings and abundance have doubled. The current policy does not consider uncertainty in the assessment. This study evaluates the impacts of uncertainty in F10% and Fcur on the status assessment of lobster fishery. Using a Monte Carlo simulation approach, we found that the status assessment would be influenced by uncertainties in estimating F10% and Fcur, and by the choice of decision confidence level reflecting the level of risk managers would like to take. A large uncertainty in Fcur and F10% and a high decision confidence level reduce the likelihood of defining the stock as overfished, and vice versa. Our results suggest that the probability of lobster overfishing may be less than previously thought, and that uncertainty in Fcur and F10% should be quantified and considered in determining the status of the GOM lobster stock.

Biological reference points for American lobster (Homarus americanus) populations: limits to exploitation and the precautionary approach

2004 ◽  
Vol 61 (8) ◽  
pp. 1392-1403 ◽  
Author(s):  
Michael J Fogarty ◽  
Louise Gendron
Keyword(s):  
United States ◽  
Egg Production ◽  
Large Scale ◽  
Abiotic Factors ◽  
Homarus Americanus ◽  
The United States ◽  
Reference Points ◽  
Population Increase ◽  
American Lobster ◽  
Precautionary Approach

Large-scale changes in American lobster (Homarus americanus) landings and abundance have been documented in both Canada and the United States over the last several decades. The spatial coherence of these changes suggests the importance of common environmental and fishery-related factors operating over broad areas in the western North Atlantic. Changes in both biotic and abiotic factors have been hypothesized to underlie the recent increases in lobster production. Area expansion of lobsters to previously unoccupied or low-density areas appears to be an important element of the population increase. Here, we review biological reference points applied to American lobster populations in the United States and Canada. Egg production per recruit models have been used to specify limit reference points (F10% in the United States) or target reference points (increasing egg production per recruit to twice its 1995 level in Canada). Surplus production and yield-per-recruit models have also been employed to provide qualitative management guidelines. We describe sources of uncertainty in the development of biological reference points for American lobster based on dynamic pool models in relation to the precautionary approach. Finally we consider auxiliary indicators and reference points with potential application to lobster stocks.

Predicting bycatch hotspots based on suitable habitat derived from fishery-independent data

2020 ◽  
Vol 641 ◽  
pp. 159-175
Author(s):  
J Runnebaum ◽  
KR Tanaka ◽  
L Guan ◽  
J Cao ◽  
L O’Brien ◽  
...  
Keyword(s):  
Habitat Suitability ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Gulf Of Maine ◽  
Homarus Americanus ◽  
Management Tool ◽  
American Lobster ◽  
Suitable Habitat ◽  
Climate Conditions ◽  
Suitability Index

Bycatch remains a global problem in managing sustainable fisheries. A critical aspect of management is understanding the timing and spatial extent of bycatch. Fisheries management often relies on observed bycatch data, which are not always available due to a lack of reporting or observer coverage. Alternatively, analyzing the overlap in suitable habitat for the target and non-target species can provide a spatial management tool to understand where bycatch interactions are likely to occur. Potential bycatch hotspots based on suitable habitat were predicted for cusk Brosme brosme incidentally caught in the Gulf of Maine American lobster Homarus americanus fishery. Data from multiple fisheries-independent surveys were combined in a delta-generalized linear mixed model to generate spatially explicit density estimates for use in an independent habitat suitability index. The habitat suitability indices for American lobster and cusk were then compared to predict potential bycatch hotspot locations. Suitable habitat for American lobster has increased between 1980 and 2013 while suitable habitat for cusk decreased throughout most of the Gulf of Maine, except for Georges Basin and the Great South Channel. The proportion of overlap in suitable habitat varied interannually but decreased slightly in the spring and remained relatively stable in the fall over the time series. As Gulf of Maine temperatures continue to increase, the interactions between American lobster and cusk are predicted to decline as cusk habitat continues to constrict. This framework can contribute to fisheries managers’ understanding of changes in habitat overlap as climate conditions continue to change and alter where bycatch interactions could occur.

Cannibals by night? In situ video monitoring reveals diel shifts in inter- and intra-specific predation on the American lobster

2013 ◽  
Vol 70 (11) ◽  
pp. 1635-1640 ◽  
Author(s):  
Noah G. Oppenheim ◽  
Richard A. Wahle
Keyword(s):  
Video Surveillance ◽  
Population Regulation ◽  
Gulf Of Maine ◽  
Homarus Americanus ◽  
Quantitative Information ◽  
Video Monitoring ◽  
Predatory Fish ◽  
American Lobster ◽  
Population Densities

We conducted tethering experiments in the field to evaluate day–night differences in the identity and frequency of predators encountered by the American lobster (Homarus americanus) in coastal Maine, USA. Separate daytime and nighttime deployments were conducted using tethered lobsters under infrared-illuminated video surveillance. Supplemental tethering trials without video surveillance provided further quantitative information on diel and size-specific predation patterns. We found crabs to be the most common predators during the day, whereas lobsters prevailed at night. Contrary to expectations, we measured higher predation rates at night than during the day, suggesting that nocturnal interactions with conspecifics may play a more important role in lobster population regulation than previously thought when lobster population densities are high and large predatory fish are rare. As large predatory groundfish have been depleted in the Gulf of Maine, lobster populations have reached historic highs, making density-dependent feedbacks such as cannibalism more likely.

Recruitment overfishing reference point for the American lobster, Homarus americanus

1997 ◽  
Vol 48 (8) ◽  
pp. 1029 ◽  
Author(s):  
G. P. Ennis ◽  
M. J. Fogarty
Keyword(s):  
Median Survival ◽  
Reference Point ◽  
Egg Production ◽  
Adult Population ◽  
Homarus Americanus ◽  
Reference Points ◽  
American Lobster ◽  
Survival Ratio ◽  
Low Level ◽  
Exploitation Rate

A 21-year series of annual estimates of egg production and recruitment in a Newfoundland lobster population indicates similar asymptotic relationships for recruitment to the fishery and to the adult population, both derived from legal stock estimates. Lines with slopes equal to the 90th-percentile and median survival ratios drawn through the origin of the egg production–adult recruitment scatterplot were examined as potential recruitment overfishing reference points for the Arnold’s Cove lobster stock. If the inverse of the estimated lifetime egg production per recruit (E/R) for a given exploitation rate exceeds the slope of the selected reference point, the risk of recruitment overfishing is high. For the Arnold’s Cove stock, the E/R level at a nominal 90% exploitation rate is estimated at 4.2% of the unfished population, compared with 2.5% for the overfishing reference point corresponding to the median survival ratio. Female lobsters at Arnold’s Cove mature at sizes below the minimum legal size, providing a buffer against high exploitation rates. Small, scattered refugia of large lobsters could also help to explain how heavily exploited populations of this species persist at such a low level of egg production.

Responsive harvest control rules provide inherent resilience to adverse effects of climate change and scientific uncertainty

2019 ◽  
Vol 76 (6) ◽  
pp. 1424-1435 ◽  
Author(s):  
J P Kritzer ◽  
C Costello ◽  
T Mangin ◽  
S L Smith
Keyword(s):  
Climate Change ◽  
Adverse Effects ◽  
Biomass Yield ◽  
The United States ◽  
Scientific Uncertainty ◽  
Fish Stock ◽  
Fishing Mortality ◽  
Climate Effects ◽  
Control Rules ◽  
Harvest Control Rules

Abstract Climate change is altering marine ecosystem and fish stock dynamics worldwide. These effects add to scientific uncertainties that compromise fisheries management. Among the strategies that can respond to climate change and scientific uncertainty, modifications to harvest control rules (HCRs) might be among the most direct and impactful. We used a bioeconomic model to compare alternative HCRs in terms of biomass, yield, and profits in response to potential effects of climate change and scientific uncertainty, specifically simulated retrospective patterns, for 14 stocks on the Northeast Shelf of the United States. Our results suggest that a responsive HCR in which fishing mortality changes with measured changes in biomass builds inherent resilience to adverse effects of both climate change and scientific uncertainty relative to an HCR in which fishing mortality is precautionary but fixed. This was despite that fact that the HCR algorithm did not account for the climate effects modelled. A fixed fishing mortality HCR was effective when climate effects were negligible or beneficial. Scientific uncertainty further reduced biomass, yield, and profits by about the same magnitude as climate change. Our results suggest that simple changes to HCRs can be a readily implementable strategy for responding to climate change and scientific uncertainty.

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