Age-at-size relationships of the American lobster (Homarus americanus) from three contrasting thermal regimes using gastric mill band counts as a direct aging technique

2020 ◽  
Vol 77 (10) ◽  
pp. 1733-1740
Author(s):  
Carl J. Huntsberger ◽  
Raouf Kilada ◽  
William G. Ambrose ◽  
Richard A. Wahle
Keyword(s):  
New England ◽  
Gulf Of Maine ◽  
Age Determination ◽  
Homarus Americanus ◽  
Gastric Mill ◽  
Band Formation ◽  
Southern New England ◽  
Thermal Regimes ◽  
The One

Direct age determination of crustaceans has remained a long-standing challenge because all calcified structures are shed with each molt. Cuticle bands in the ossicles of the gastric mill have shown promise as age indicators. We validated the one-to-one relationship between known age and number of cuticle bands for 15 hatchery-raised juvenile American lobsters (Homarus americanus). Additionally, we applied this method to 308 lobsters from three contrasting thermal regimes in New England, USA. Band counts matched our expectations of differences in age-at-size across this thermal gradient; lobsters at harvestable size in southern New England were estimated to be 5.5 (±1.5) years old compared with 7.5 (±1.6) years in the Gulf of Maine. We found 81% of our band count estimates of age fell within 2 years of independent, regionally specified growth model estimates of age-at-size for lobster. Notwithstanding remaining uncertainties regarding the mechanism of band formation, our findings indicate the method may provide an independent and direct means to determine the age of individual American lobsters, which will improve estimates of essential life history parameters.

scholarly journals Directly ageing the Caribbean spiny lobster, Panulirus argus with validated band counts from gastric mill ossicles

2018 ◽  
Vol 76 (2) ◽  
pp. 442-451 ◽  
Author(s):  
Gaya Gnanalingam ◽  
Mark J Butler ◽  
Thomas R Matthews ◽  
Emily Hutchinson ◽  
Raouf Kilada
Keyword(s):  
Spiny Lobster ◽  
Age Determination ◽  
Florida Keys ◽  
Panulirus Argus ◽  
Gastric Mill ◽  
Coefficients Of Variation ◽  
The Caribbean ◽  
First Time ◽  
Reader Experience

Abstract In crustaceans, ecdysis was long believed to result in the loss and replacement of all calcified structures, precluding the use of conventional ageing methods. However, the discovery of bands in the gastric ossicles of several crustaceans with some correlation with age suggests that direct age estimation may be possible. We applied this method to a tropical spiny lobster, Panulirus argus, one of the most iconic and economically valuable species in the Caribbean. The presence of growth bands was investigated using wild lobsters of unknown age and was validated with captive reared lobsters of known age (1.5–10 years) from the Florida Keys, Florida (USA). Bands were consistently identified in ptero- and zygo-cardiac ossicles of the gastric mill and did not appear to be associated with moulting. Validation with known age animals confirms that bands form annually. Counts between independent readers were reproducible with coefficients of variation ranging from 11% to 26% depending on reader experience and the structure used. This study demonstrates, for the first time, that direct age determination of P. argus is possible.

scholarly journals American lobster nurseries of southern New England receding in the face of climate change

2015 ◽  
Vol 72 (suppl_1) ◽  
pp. i69-i78 ◽  
Author(s):  
Richard A. Wahle ◽  
Lanny Dellinger ◽  
Scott Olszewski ◽  
Phoebe Jekielek
Keyword(s):  
New England ◽  
Rhode Island ◽  
Size Composition ◽  
Homarus Americanus ◽  
Warming Trend ◽  
Shore Crab ◽  
American Lobster ◽  
Southern New England ◽  
Study Sites ◽  
Outer Coast

Abstract Historically, southern New England has supported one of the most productive American lobster (Homarus americanus) fisheries of the northeast United States. Recently, the region has seen dramatic declines in lobster populations coincident with a trend of increasingly stressful summer warmth and shell disease. We report significant declines in the abundance, distribution, and size composition of juvenile lobsters that have accompanied the warming trend in Narragansett Bay, Rhode Island, since the first comprehensive survey of lobster nurseries conducted there in 1990. We used diver-based visual surveys and suction sampling in 1990, 2011, and 2012, supplemented by post-larval collectors in 2011 and 2012. In 1990, lobster nurseries extended from the outer coast into the mid-sections of the bay, but by 2011 and 2012 they were largely restricted to the outer coast and deeper water at the mouth of the bay. Among five new study sites selected by the lobster fishing industry for the 2011 and 2012 surveys, the deepest site on the outer coast (15–17 m depth) harboured some of the highest lobster densities in the survey. Separate fixed site hydrographic monitoring at 13 locations in the bay by the Rhode Island Division of Fish and Wildlife recorded an approximately 2.0°C increase in summer surface temperatures over the period, with 2012 being the warmest on record. Additional monitoring of bottom temperatures, dissolved oxygen and pH at our sampling sites in 2011 and 2012 indicated conditions falling below physiological optima for lobsters during summer. The invasion of the Asian shore crab, Hemigrapsus sanguineus, since the 1990s may also be contributing to declines of juvenile lobster shallow zones (<5 m) in this region. Because lobster populations appear increasingly restricted to deeper and outer coastal waters of southern New England, further monitoring of settlement and nursery habitat in deep water is warranted.

scholarly journals Northeast Bathymetry and Backscatter Compilation: Western Gulf of Maine, Southern New England, and Long Island Sound

2021 ◽  
Author(s):  
Larry Ward ◽  
Paul Johnson ◽  
Michael Bogonko ◽  
Zachary McAvoy ◽  
Rachel Morrison
Keyword(s):  
New England ◽  
Gulf Of Maine ◽  
Long Island ◽  
Long Island Sound ◽  
Southern New England ◽  
Island Sound

scholarly journals Effects of excluding bottom-disturbing mobile fishing gear on abundance and biomass of groundfishes in the Stellwagen Bank National Marine Sanctuary, USA

2010 ◽  
Vol 56 (1) ◽  
pp. 134-143 ◽  
Author(s):  
Briana K. Brown ◽  
Elizabeth Soule ◽  
Les Kaufman
Keyword(s):  
New England ◽  
Fishery Management ◽  
Gulf Of Maine ◽  
Fishing Gear ◽  
Fine Scale ◽  
Benthic Habitats ◽  
Fall Season ◽  
The One ◽  
Management Council ◽  
Sampling Season

Abstract The Stellwagen Bank National Marine Sanctuary (southern Gulf of Maine, northwest Atlantic) is partially overlapped by the Western Gulf of Maine Closure Area (WGMCA). This is a region in which mobile, bottom-disturbing fishing gear has been banned by the New England Fishery Management Council to facilitate the rebuilding of depleted groundfish populations. We assessed the effects and effectiveness of the WGMCA on groundfish assemblages using habitat-stratified (gravel, sand, mixed benthic habitats) sampling by means of a commercial trawler, inside and outside of the WGMCA. Sampling occurred over three month-long sampling periods in 2004-2005, two during the spring seasons and one during the fall season. A total of 18 species were analyzed for protection effects. After controlling for substratum, location and sampling season, eight groundfish species exhibited higher mean proportional abundance inside than outside the WGMCA while two were proportionally more abundant on average outside of the closure. Four species had higher mean proportional biomasses on average inside the closure and three outside. We conclude that the WGMCA may be achieving its goal of rebuilding abundance and biomass for some commercially targeted groundfishes but not all. This study, six to seven years post-closure establishment, reveals fine-scale spatial and taxonomic complexity which will require a very different monitoring protocol than the one currently in place if adaptive management is to be successful in the region.

Discrimination of American lobster (Homarus americanus) stocks off southern New England on the basis of secondary sex character allometry

1995 ◽  
Vol 52 (12) ◽  
pp. 2712-2723 ◽  
Author(s):  
Steven X. Cadrin
Keyword(s):  
New England ◽  
Principal Components ◽  
Principal Component ◽  
Homarus Americanus ◽  
American Lobster ◽  
Multiple Group ◽  
Southern New England ◽  
Female Data ◽  
Components Analysis ◽  
Component Scores

Male American lobster (Homarus americanus) from inshore southern New England were discriminated from offshore males on the basis of larger relative chela size. Lobsters from Buzzards Bay (inshore) had more conspicuous sexual dimorphism than lobsters from Hydrographer Canyon (offshore), and allometric growth of male chelae was more prominent than that of female abdomens. Principal components analysis of males from combined stocks represented variability in multivariate size and relative chela size, and component score distributions of each stock were discrete. Principal components of females from both stocks comprised variability in overall size and relative abdomen size, but principal component scores overlapped extensively. Multiple-group principal component 2 was a size-free index of relative chela size that classified 96% of males to the correct stock. Multiple-group principal component 2 of females did not successfully separate stocks. Discriminant analysis of size-adjusted morphometric data classified males to stock with 100% accuracy on the basis of relative chela size. Although discrimination of size-adjusted female data classified stocks with 94% accuracy, it was less stable and not associated with onset of maturity.

Age, growth, and latitudinal patterns of two Rajidae species in the northwestern Atlantic: little skate (Leucoraja erinacea) and winter skate (Leucoraja ocellata)

2006 ◽  
Vol 63 (5) ◽  
pp. 1078-1091 ◽  
Author(s):  
Michael G Frisk ◽  
Thomas J Miller
Keyword(s):  
New England ◽  
Gulf Of Maine ◽  
Growth Curves ◽  
Von Bertalanffy ◽  
Southern New England ◽  
Asymptotic Size ◽  
Cape Hatteras ◽  
Northern Regions ◽  
Significant Length ◽  
Latitudinal Patterns

Vertebral samples of little skate (Leucoraja erinacea) and winter skate (Leucoraja ocellata) were collected from Cape Hatteras, USA, to Canadian waters to estimate age, growth, and length at weight relationships for both species throughout this range. Maximum observed age was 12.5 and 20.5 years for little skate and winter skate, respectively. Significant length at weight relationships were found for both species. von Bertalanffy growth curves for the northwestern Atlantic were estimated for little skate (k = 0.19, L∞ = 56.1 cm, t0 = –1.17, p < 0.0001, n = 236) and winter skate (k = 0.07, L∞ = 122.1 cm, t0 = –2.07, p < 0.0001, n = 229). Additionally, latitudinal patterns in size and growth were observed in little skate, with individuals in northern regions growing slower and reaching a larger asymptotic size: von Bertalanffy growth estimates (mid-Atlantic, k = 0.22, L∞ = 53.26 cm, t0 = –1.04, p < 0.0001; southern New England – Georges Bank, k = 0.20, L∞ = 54.34 cm, t0 = –1.22, p < 0.0001; Gulf of Maine, k = 0.18, L∞ = 59.31 cm, t0 = –1.15, p < 0.0001). Although differences were observed for sex-specific growth curves for both species, only winter skate curves were significantly different.

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