Large-scale and long-term, spatial and temporal patterns in demography and landings of the American lobster, Homarus americanus, in Maine

2001 ◽  
Vol 52 (8) ◽  
pp. 1303 ◽  
Author(s):  
Robert S. Steneck ◽  
Carl J. Wilson
Keyword(s):  
Gulf Of Maine ◽  
Temporal Patterns ◽  
Homarus Americanus ◽  
American Lobster ◽  
Cold Spot ◽  
Spatial And Temporal Patterns ◽  
Population Densities ◽  
North East ◽  
Catch Rates ◽  
Penobscot Bay

The American lobster, Homarus americanus, is abundant (>1/m2) in spatially complex coastal habitats of the Gulf of Maine. Quadrat surveys (stratified by exposure, depth, and substrate) conducted at fixed locations since 1989 revealed consistently higher lobster population densities west and south of Penobscot Bay in central Maine. High-resolution surveys in 1999 at 70 closely spaced dive sites revealed distinct settlement hot spots and cold spots, stable over several years at least. Densest settlement occurred along a 100-km outer coastal region westward from the mouth of Penobscot Bay. A settlement cold spot about 60-km in diameter was evident in the north-east corner of Penobscot Bay. Abundance of older, adolescent-phase, lobsters (40–90 mm carapace length, CL) corresponded with patterns of settlement. Catch rates per trap haul of prerecruits (< 83 mm CL) and catch rates per area for lobsters fully recruited to the fishery (83 mm CL) correspond with local lobster densities. Until recently, populations increased in three of four regions over the past decade, most strongly in north-eastern Maine. Landings per length of coastline corresponded to spatial and temporal patterns of abundance. Consistent spatial and temporal patterns suggest that population densities can be reliably determined from calibrated fisherydependent data.

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.

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.

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.

scholarly journals A field-based investigation of behavioural interactions between invasive green crab (Carcinus maenas), rock crab (Cancer irroratus), and American lobster (Homarus americanus) in southern Newfoundland

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8444
Author(s):  
Nicola Zargarpour ◽  
Cynthia H. McKenzie ◽  
Brett Favaro
Keyword(s):  
Carcinus Maenas ◽  
Positive Association ◽  
Homarus Americanus ◽  
Green Crab ◽  
American Lobster ◽  
Catch Per Unit Effort ◽  
Cancer Irroratus ◽  
Species Invasions ◽  
Rock Crab ◽  
Catch Rates

Marine species invasions pose a global threat to native biodiversity and commercial fisheries. The European green crab (Carcinus maenas) is one of the most successful marine invaders worldwide and has, in the last decade, invaded the southern and western coastal waters of the island of Newfoundland, Newfoundland and Labrador (NL), Canada. Impacts of green crab on the American lobster (Homarus americanus), which are native to Newfoundland, are not well understood, particularly for interactions around deployed fishing gear. Declines in lobster catch rates in invaded systems (i.e., Placentia Bay, NL), have prompted concerns among lobster fishers that green crab are interfering with lobster catch. Here, we conducted a field experiment in a recently-invaded bay (2013) in which we deployed lobster traps pre-stocked with green crab, native rock crab (Cancer irroratus) (a procedural control), or empty (control). We compared catch per unit effort across each category, and used underwater cameras to directly observe trap performance in situ. In addition, we used SCUBA surveys to determine the correlation between ambient density of lobster and green crab in the ecosystem and the catch processes of lobster in traps. We found: (1) Regardless of the species of crab stocked, crab presence reduced the total number of lobster that attempted to enter the trap, and also reduced entry success rate, (2) lobster consumed green crab, rock crab and other lobster inside traps and (3) there was a positive association between lobster catch and ambient lobster density. Our results suggest that while there was a relationship between in-trap crab density and trap catch rates, it was not linked to the non-native/native status of the crab species.

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.

Using acoustic telemetry to observe the effects of a groundfish predator (Atlantic cod, Gadus morhua) on movement of the American lobster (Homarus americanus)

2013 ◽  
Vol 70 (11) ◽  
pp. 1625-1634 ◽  
Author(s):  
Marissa D. McMahan ◽  
Damian C. Brady ◽  
Diane F. Cowan ◽  
Jonathan H. Grabowski ◽  
Graham D. Sherwood
Keyword(s):  
Home Range ◽  
Behavioral Response ◽  
Acoustic Telemetry ◽  
Gadus Morhua ◽  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Homarus Americanus ◽  
American Lobster ◽  
Habitat Area ◽  
Predation Rates

American lobster (Homarus americanus) landings have more than quadrupled in the last two decades (1990–2010), coinciding with the collapse of Gulf of Maine groundfish fisheries such as Atlantic cod (Gadus morhua). Recently there has been speculation that the release of lobster from predatory control may have resulted in both lower predation rates and increased foraging areas. We used fine-scale acoustic telemetry within a 200 m × 250 m field enclosure to test the hypothesis that cod induce lobsters to decrease movement and seek refuge. We found a large amount of variation in the behavioral response of individual lobsters to predators; however, the addition of cod into the enclosure reduced maximum daily home range area and significantly reduced the distance traveled from shelter habitat area for all individuals. When predators were removed from the enclosure, lobsters responded by increasing home range area and significantly increasing the distance traveled from shelter habitat area. These results represent the first experimental evidence for American lobster range contraction and subsequent expansion in the presence and absence of cod, respectively.

Quantitative relationships between postlarval production and benthic recruitment in lobsters, Homarus americanus

1997 ◽  
Vol 48 (8) ◽  
pp. 729 ◽  
Author(s):  
Lewis S. Incze ◽  
Richard A. Wahle ◽  
J. Stanley Cobb
Keyword(s):  
Rhode Island ◽  
Annual Variation ◽  
Gulf Of Maine ◽  
Homarus Americanus ◽  
Seasonal Abundance ◽  
Moult Cycle ◽  
American Lobster ◽  
Temperature Dependent ◽  
Dependent Growth ◽  
Island Sound

Relationships between lobster postlarval supply and benthic recruitment were evaluated within and between oceanographically distinct segments of the range of the American lobster. Postlarvae (PL) were sampled by neuston nets in western Rhode Island Sound and the western Gulf of Maine, USA, from June to September 1989–95. Benthic lobsters were sampled in sublittoral cobble habitat by using a diver-operated airlift at the end of the settlement season. Average annual recruitment densities of young-of-year (YOY) lobsters ranged from 0.3 to 1.7 m-2. YOY recruitment was positively correlated between areas. Integrated seasonal abundance of postlarvae was often much greater in Rhode Island than Maine, but production estimates (PL 1000 m-2 season-1), calculated from moult cycle stages and temperature-dependent growth rates, differed by a factor of <0.5. PL production was positively correlated between areas and explained ≥81% of the annual variation in recruitment in each area and 90% for the two areas combined. In Maine, among-site differences in YOY recruitment persisted for a year after settlement and then began to lessen, at least in part because larger individuals moved into areas of initially lower recruitment

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