A comparison of the size at maturity of female American lobsters (Homarus americanus) over three decades and across coastal areas of the Gulf of Maine using ovarian staging

2021 ◽  
Author(s):  
Jesica D Waller ◽  
Kathleen M Reardon ◽  
Sarah E Caron ◽  
Blaise P Jenner ◽  
Erin L Summers ◽  
...  
Keyword(s):  
Egg Production ◽  
Gulf Of Maine ◽  
Stock Assessment ◽  
Coastal Region ◽  
Homarus Americanus ◽  
Growth Patterns ◽  
American Lobster ◽  
Size At Maturity ◽  
Management Measures ◽  
Production Growth

Abstract The carapace length (CL) at which American lobster (Homarus americanus) females reach maturity can be used to evaluate egg production, growth patterns, and the overall health of lobster stocks. The female maturity datasets used to represent Gulf of Maine (GOM) lobsters in the 2015 Atlantic States Marine Fisheries Commission American Lobster Stock Assessment were collected in the 1990s by the Maine Department of Marine Resources at two coastal sites. Many studies have demonstrated an inverse relationship between temperature and the size at maturity in female lobsters, and GOM waters have warmed significantly over this period. To update these GOM maturity datasets, we used ovarian staging to determine the maturity status of over 1200 females from fives sites over 3 years. Broad application of this methodology in tandem with key growth measurements on females 50–120 mm CL allowed us to characterize reproductive development and generate maturity ogives (proportion mature at a given CL). We observed a latitudinal gradient in the size at maturity across this coastal region of the GOM and quantified a decrease in this size over 25 years. These findings have implications for future stock assessment approaches and management measures implemented to sustain this valuable fishery.

Decrease in size at maturity of female American lobsters Homarus americanus (H. Milne Edwards, 1837) (Decapoda: Astacidea: Nephropidae) over a 50-year period in Maine, USA

2019 ◽  
Vol 39 (4) ◽  
pp. 509-515 ◽  
Author(s):  
Jesica D Waller ◽  
Kathleen M Reardon ◽  
Sarah E Caron ◽  
Henry M Masters ◽  
Erin L Summers ◽  
...  
Keyword(s):  
Egg Production ◽  
Gulf Of Maine ◽  
Stock Assessment ◽  
Homarus Americanus ◽  
Assessment Method ◽  
Cement Gland ◽  
Assessment Model ◽  
Size At Maturity ◽  
Significant Difference ◽  
Bank Stock

ABSTRACTThe size at which female American lobsters Homarus americanus (H. Milne Edwards, 1837) reach maturity was determined for females collected from inshore (< 3 nautical miles, or 5.5 km) Boothbay Harbor (BBH), Maine, USA in 2018. A total of 272 females were collected during a three-week period in the spring and each female was assigned a maturity status (immature or mature) based on ovarian staging. These determinations were then compared to two similar female-maturity studies undertaken in BBH by the Maine Department of Marine Resources over the last 50 years. The comparison revealed that the length at which 50% of females reach maturity has decreased by 5 mm over the last 25 years and a significant difference between maturity ogives generated over time in BBH. Cement-gland stage was also recorded for all females and further analysis revealed no significant difference between maturity ogives generated using ovarian and cement-gland staging. Results indicate that cement-gland staging is an effective maturity assessment method in female lobsters from this region. Because there is a well-documented relationship between temperature and size at maturity in crustaceans, we also examined changes in sea-surface temperature during this period in BBH. We found that the region has warmed significantly over this period of time with extreme high temperatures occurring more frequently during the last 25 years. Our results can be used to update key parameters in the stock-assessment model related to growth and egg production in the Gulf of Maine/George’s Bank stock. These findings can also be used to inform future management decisions related to the carapace length of harvested lobsters and the preservation of mature females.

Female American lobster (Homarus americanus) size-at-maturity declined in Canada during the 20th and early 21st centuries

2018 ◽  
Vol 75 (6) ◽  
pp. 908-924 ◽  
Author(s):  
Marthe Larsen Haarr ◽  
Bernard Sainte-Marie ◽  
Michel Comeau ◽  
M. John Tremblay ◽  
Rémy Rochette
Keyword(s):  
Egg Production ◽  
Homarus Americanus ◽  
American Lobster ◽  
Past Century ◽  
Female Size ◽  
Strongly Correlated ◽  
Size At Maturity ◽  
The Past ◽  
Evolutionary Response ◽  
Intense Exploitation

Changes in the environment and fishing have been shown to affect life-history characteristics, such as size or age of maturation, in a number of finfish and invertebrates. The American lobster (Homarus americanus) supports Canada’s most valuable fishery and exploitation rates are high. Female size-at-maturity (SM) is an important parameter in management of this species, as it is used in establishing minimum legal size regulations. In this study, we show with historical and recent data that SM of female American lobsters has declined across most of Canada, in some areas by as much as 30%, over the past 10–80 years. The spatial patterns of these declines are inconsistent with patterns of rising ocean temperature and lobster abundance (density). They are, however, strongly correlated to the strength of size-based fishery selection, and egg-per-recruit modeling indicates a gain in lifetime egg production associated with observed SM declines under a range of realistic harvesting scenarios. These findings suggest that the marked decrease we document in SM of female American lobsters in Canada over the past century represents an evolutionary response to intense exploitation.

scholarly journals Using an individual-based model to simulate the Gulf of Maine American lobster (Homarus americanus) fishery and evaluate the robustness of current management regulations

2019 ◽  
Vol 76 (10) ◽  
pp. 1709-1718 ◽  
Author(s):  
Mackenzie Mazur ◽  
Bai Li ◽  
Jui-Han Chang ◽  
Yong Chen
Keyword(s):  
Gulf Of Maine ◽  
Stock Assessment ◽  
Probabilistic Approach ◽  
Size Composition ◽  
Homarus Americanus ◽  
American Lobster ◽  
Current Management ◽  
Complex Processes ◽  
Individual Based Models ◽  
Complex Life History

Individual-based models (IBMs) can capture complex processes with a flexible probabilistic approach, which makes them useful for studying organisms with complex life history and fishery processes such as the American lobster (Homarus americanus). This research aims to modify and parameterize an individual-based lobster simulator (IBLS) to simulate the American lobster fishery in the Gulf of Maine. To simulate the fishery, the IBLS was tuned to match the seasonal catch and size composition from the 2015 American lobster stock assessment by adjusting the values of coefficients for select parameters. With appropriate coefficients for the initial abundance, recruitment, and seasonal encounter probability levels, the tuned IBLS accurately simulated the historical landings. Given the uncertainty in future American lobster recruitment, the tuned IBLS was then used to evaluate the effectiveness of current management regulations under different levels of recruitment.

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.

Changes in female lobster (Homarus americanus) size at maturity and implications for the lobster resource in Long Island Sound, Connecticut

2001 ◽  
Vol 52 (8) ◽  
pp. 1283 ◽  
Author(s):  
Donald F. Landers Jr ◽  
Milan Keser ◽  
Saul B. Saila
Keyword(s):  
Sexual Maturity ◽  
Egg Production ◽  
Long Island ◽  
Homarus Americanus ◽  
Long Island Sound ◽  
Female Size ◽  
Size At Maturity ◽  
Size At Sexual Maturity ◽  
Average Size ◽  
Island Sound

Population theory predicts that, under conditions of high age/size-specific mortality rates, individuals in highly exploited populations increase their fitness by decreasing size at sexual maturity, relative to less exploited populations. The benefit of early reproductive maturation is that individuals have a higher probability of surviving to maturity and contributing progeny to maintain the population. Empirical evidence, based on morphometric data from nearly 60 000 female lobsters collected since 1981, suggests that size at sexual maturity of female lobsters in Long Island Sound (USA) has recently decreased. Our findings were supported by decreases in average size and increases in abundance of egg-bearing females over the past two decades. Changes in female size at maturity and subsequent higher egg production may also help to explain the recent increase in lobster recruitment and landings. It is unclear whether these changes were caused by density-dependent factors related to the high exploitation of the species, by natural environmental factors (e.g. higher seawater temperatures), or a combination of the two.

Stock Definition, Recruitment Variability, and Larval Recruitment Processes in the American Lobster, Homarus americanus: A Review

1986 ◽  
Vol 43 (11) ◽  
pp. 2072-2084 ◽  
Author(s):  
G. P. Ennis
Keyword(s):  
Egg Production ◽  
Homarus Americanus ◽  
Ecosystem Change ◽  
American Lobster ◽  
Surface Currents ◽  
Larval Supply ◽  
Review Of The Literature ◽  
Larval Recruitment ◽  
Change Mechanisms ◽  
Standing Stocks

A review of the literature pertaining to stock definition, causes of variability in recruitment to standing stocks, and larval recruitment processes in the American lobster, Homarus americanus, is presented. Several stocks can be identified but their boundaries are indistinct. The areas are too large for consideration of any of the stocks as a single management unit. The bulk of annual landings is composed of recruitment to standing stocks since the preceding fishing season. Landings for all areas fluctuate and there is considerable variability in patterns of fluctuations between areas. Suggested causes of variability in recruitment include variation in temperature, variation in annual river discharge, fishery induced variability in egg production, man-made interruption in larval supply, and ecosystem change. Mechanisms that determine where larvae that originate in a given area eventually settle are uncertain. Literature on larval recruitment processes contains theories based on passive transport of larvae by surface currents and others based on interacting behavioral and hydrographic mechanisms that may enable larvae to maintain position near parental grounds.

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