Spatial and temporal patterns in the sex ratio of American lobsters (Homarus americanus) in southwestern Nova Scotia, Canada

Koepper, Svenja; Revie, Crawford W.; Stryhn, Henrik; Clark, Kevin; Scott-Tibbetts, S.; Thakur, Krishna K.

doi:10.1038/s41598-021-03233-8

Cited by 8 publications

(10 citation statements)

References 53 publications

(77 reference statements)

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“…Only one bacterial taxon had a significantly different abundance between male, female and berried female lobsters. Observing no significant differences in the alpha and beta diversity of the shell microbiome between lobster sex and size was somewhat surprising, as berried females and larger lobsters molt less often and have different preferred habitats ( Cobb, 1976 ; Castro and Somers, 2012 ; Koepper et al, 2021 ). A longer time in their shell could imply a distinct microbial community as bacterial taxa, including pathogenic taxa, have more time to proliferate and colonize the carapace, but this was not observed here.…”

Section: Discussionmentioning

confidence: 99%

Differences in diversity and community composition of the shell microbiome of apparently healthy lobsters Homarus americanus across Atlantic Canada

Koepper,

Clark,

McClure

et al. 2024

Front. Microbiol.

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Host-microbe dynamics are of increasing interest in marine research due to their role in host health and productivity. Changes in the shell microbiome of American lobsters have been associated with epizootic shell disease, a syndrome that is spreading northwards across the eastern U.S. and Canadian Atlantic coast. This study analyzed differences in alpha and beta diversity, as well as differentially abundant taxa, in the shell-associated bacterial community of apparently healthy lobsters from four lobster fishing areas (LFAs) in Atlantic Canada. Over 180 lobsters from New Brunswick, Nova Scotia and Prince Edward Island (PEI) were sampled during seven sampling events over four sampling months. The bacterial community was identified using novel PacBio long-read sequencing, while alpha and beta diversity parameters were analyzed using linear regression models and weighted UniFrac distances. The bacterial richness, diversity and evenness differed by sampling location, sampling month, and molt stage, but not by lobster sex or size, nor sampling depth. Similarly, based on LFA, sampling month, year and lobster molt stage, the shell microbiome differed in microbial community composition with up to 34 out of 162 taxa differing significantly in abundance between sampling groups. This large-scale microbial survey suggests that the shell microbial diversity of apparently healthy lobsters is influenced by spatial and temporal factors such as geographic location, as well as the length of time the carapace is exposed to the surrounding seawater.

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Section: Discussionmentioning

confidence: 99%

Differences in diversity and community composition of the shell microbiome of apparently healthy lobsters Homarus americanus across Atlantic Canada

Koepper,

Clark,

McClure

et al. 2024

Front. Microbiol.

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“…Sex ratio can also be affected by localized environmental factors, such as temperature, since mature females tend to favor cooler, deeper waters than males at certain times of the year (Crossin et al 1998; Cowan et al 2007). Koepper et al (2021) found that a combination of fishing pressure and environmental factors affect sex ratios in Nova Scotia waters, with female‐skewed sex ratios occurring in areas of high fishing effort and cooler, deeper waters. It is possible, therefore, that future reductions of fishing effort in the Monument will modify sex ratios, presumably towards a lower proportion of females if male‐biased fishing mortality is reduced.…”

Section: Discussionmentioning

confidence: 99%

“…Sex ratio varies widely across the American lobster species' range (ASMFC 2020; Koepper et al 2021). It is influenced by harvesting pressure since males generally incur higher fishing mortality than females, which can ultimately lead to sperm limitation if populations become heavily female biased (MacDiarmid and Butler 1999; Pardo et al 2015).…”

Section: Discussionmentioning

confidence: 99%

American lobster and Jonah crab populations inside and outside the Northeast Canyons and Seamounts Marine National Monument, USA

Arnott,

Long,

Ellertson

et al. 2023

Mar Coast Fish

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ObjectiveThere is international pressure to increase the worldwide expanse of marine protected areas (MPAs). However, MPAs often lack preexisting long‐term biological baselines, which are essential for assessing MPA effects and for refining the conservation and socioeconomic benefits they confer to society. Our study addresses this issue by establishing demographic baselines for two commercially important species prior to a proposed fishing ban inside the Northeast Canyons and Seamounts Marine National Monument, a recently established MPA on the continental shelf break approximately 200 km southeast of Cape Cod, Massachusetts.MethodsSamples were obtained by the Commercial Fisheries Research Foundation's American Lobster and Jonah Crab Research Fleet, which is an industry‐based, fishery‐dependent data collection program. Specially trained participants recorded year‐round biological data from their 2013 to 2021 commercial catches of American lobster Homarus americanus and Jonah crab Cancer borealis. Samples were taken from an area inside the MPA and from two areas outside the MPA, spanning 130 km to the east and west.ResultAmerican lobster sizes and sex ratios varied between areas, and their sizes, sex ratios, and proportion of ovigerous females differed between submarine canyons within areas. American lobster sizes, sex ratio, proportion of ovigerous females, and prevalence of shell disease were also affected by season and/or depth. Jonah crab parameters did not vary between areas, but sex ratio varied with season and depth, and the proportion of ovigerous females varied with depth.ConclusionThese demographic baselines are the only data available, at a sufficient spatial and temporal resolution, for evaluating the effects of a proposed fishing ban in the MPA, and they fill important data gaps for stock assessments. To evaluate possible future population changes, it will be necessary to continue collecting data from inside and outside the MPA using comparable methods, and to account for the preexisting sources of variation that we have identified.

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“…Statistical data on capture productions of Charybdis species in the China Fishery Statistical Yearbooks are the only resource nation contributing to FAO fishery statistics and have been available since 2003. A declining trend in capture productions of Charybdis species has been noticed from approximately 12% (~72,000 t) of the annual total swimming crab production in 2003 to <4% (~22,000 t) in 2020 (MOA, 2003-2017, MARA, 2018-2021. However, studies from reproductive biology and population structure to fishery patterns on Charybdis species are limited, irrespective of their commercial importance in crustacean fisheries.…”

Section: Introductionmentioning

confidence: 99%

Population structure and reproductive dynamics of the ridged swimming crab Charybdis natator in the southern Taiwan Strait of China: significant changes within 25 years

2023

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The ridged swimming crab Charybdis natator (Portunidae) is a commercially important crustacean species in China. The purpose of this study is to compare its population structure and reproductive pattern within the same fishing area (the southern Taiwan Strait) from two datasets over 25 years; one from 1994−1996 (the early years of the C. natator fishery) and the other from 2019. The overall sex ratio (male:female) changed from a male bias (1:0.76, p < 0.01) in 1994−1996 to a female bias (1:1.38, p < 0.01) in 2019. Male body sizes (carapace width, CW) were significantly larger than those of females in both datasets (p < 0.05). The average CW and body weight (BW) of males and females in 2019 were significantly smaller (p < 0.01) and lighter (p < 0.01) than those in 1994−1996. The maximum body size and the proportion of large-sized individuals (CW > 10 cm) decreased dramatically over 25 years. One spawning peak season was identified from each dataset, i.e., March−August 1994−1996 and February−April 2019, revealing a 1-month shift. The minimum body sizes for female maturation (carrying eggs) were 6.9 cm CW in 1994−1996 and 6.1 cm CW in 2019, an 11.6% reduction over 25 years. For the first time, the CW at 50% female maturation, the relationship between female absolute fecundity and CW, and egg diameters were obtained from the 2019 dataset, which can be applied in the future comparisons. Recent studies have revealed a consistent spawning peak in February–April for several commercially important crabs in the southern Taiwan Strait. These findings should be considered in crab fishery management. Furthermore, both fishery- and environment-associated factors influencing crustacean population structure and reproductive dynamics merit further investigation.

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Spatial and temporal patterns in the sex ratio of American lobsters (Homarus americanus) in southwestern Nova Scotia, Canada

Cited by 8 publications

References 53 publications

Differences in diversity and community composition of the shell microbiome of apparently healthy lobsters Homarus americanus across Atlantic Canada

Differences in diversity and community composition of the shell microbiome of apparently healthy lobsters Homarus americanus across Atlantic Canada

American lobster and Jonah crab populations inside and outside the Northeast Canyons and Seamounts Marine National Monument, USA

Population structure and reproductive dynamics of the ridged swimming crab Charybdis natator in the southern Taiwan Strait of China: significant changes within 25 years

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