Pugh T.L.,0 Emerson Avenue |
Comeau M.,Gulf |
Watson W.H.,Gulf |
Benhalima K.,University of New Hampshire
Journal of Crustacean Biology | Year: 2015
Variation in the quality of ejaculate produced by male American lobsters, Homarus americanusMilne Edwards, 1837, has been previously described, but never quantified. This study examined the size and composition of ejaculates produced by 111 males ranging from 60 to 108 mm in carapace length (CL). Ejaculates were obtained via electrical stimulation, photographed and then processed for histology. Half of the males produced an ejaculate from each gonopore, 29% produced only one ejaculate, and the remainder (21%) produced none. Males as small as 64 mm CL produced an ejaculate containing sperm. Ejaculate weight increased with male size, but there was a negative relationship between ejaculate weight and the percent of the ejaculate that was composed of sperm mass. Variation observed in the size and composition of ejaculates produced by similarly-sized males indicates that not all males invest equally in reproduction. Additionally, larger males may invest disproportionately more in the sperm plug (acellular component), possibly as paternal assurance. © 2015 by The Crustacean Society. Published by Brill NV, Leiden.
Elzey S.P.,0 Emerson Avenue |
Rogers K.A.,0 Emerson Avenue |
Trull K.J.,0 Emerson Avenue
Fishery Bulletin | Year: 2015
Multiple structures can be used for the age determination of fishes. Choosing the structure that provides the most precise ages is important for the provision of consistent data for the management of commercially and recreationally important species, such as the American shad (Alosa sapidissima). In this study, we compared the precision of age estimates obtained from sagittal otoliths, vertebrae, scales, and opercula as structures for the age determination of American shad. Two readers examined structures removed from 462 American shad, which were collected from the Merrimack River in Lawrence, Massachusetts, during May and June of 2008–2010. The precision of age estimates were evaluated by comparisons of ages from different readers and structures. Age estimates determined from otoliths were the most precise (76.2% agreement, 2.99% coefficient of variation). Ages derived from scales were overestimated in young (≤5 years) fish and underestimated in older (≥7 years) fish, compared with ages determined from otoliths. Age estimates determined from vertebrae agreed with those obtained from otoliths better than ages from any other structure tested, but they were less precise and vertebrae required more processing than otoliths. Opercula were difficult to read, resulting in underestimation of the ages of fish that were age 5 and older. The results of this study indicate that the sagittal otolith is the most appropriate structure for determining the age of American shad. © 2015, Fishery Bulletin. All rights reserved.
Elzey S.P.,0 Emerson Avenue |
Trull K.J.,0 Emerson Avenue
Fishery Bulletin | Year: 2016
Aging of tautog (Tautoga onitis) has historically required sacrificing fish to obtain opercula and otoliths. Use of these structures for age determination has hindered researchers from obtaining samples from fish that were to be released alive, as well as from commercially collected fish that are commonly sold whole. In this study we evaluated the use of scales, dorsal-fin spines, pelvic-fin spines, opercula, whole sagittal otoliths, and sectioned sagittal otoliths as structures for age determination of tautog. Our results indicate that pelvic-fin spines provide high-precision age estimates without bias. Dorsal-fin spines had well-defined annuli, but vascularization near the core prevented consistent identification of the first annulus and led to biased ages. Scales were difficult to read and provided highly biased ages in older (>age 7) fish. The precision of age estimations derived from pelvic-fin spines was better than the precision of age estimations derived from the other structures. Pelvic-fin spines provide suitable age estimates for tautog, and these structures can be collected easily from a wider variety of sample sources than can the structures currently being collected for age determination of this species. © 2016, National Marine Fisheries Service. All rights reserved.
Bethoney N.D.,University of Massachusetts Dartmouth |
Stokesbury K.D.E.,University of Massachusetts Dartmouth |
Schondelmeier B.P.,0 Emerson Avenue |
Hoffman W.S.,0 Emerson Avenue |
Armstrong M.P.,0 Emerson Avenue
North American Journal of Fisheries Management | Year: 2014
In the U.S. northwest Atlantic, the incidental catch of river herring (Alewife Alosa pseudoharengus and Blueback Herring A. aestivalis) by midwater trawl vessels targeting Atlantic Herring Clupea harengus and Atlantic Mackerel Scomber scombrus has become a concern for river herring conservation. Reduction of this incidental catch is a focus of fisheries managers, but information about river herring bycatch is limited. To improve the information available to fishery managers, we combined portside and at-sea observations to examine (1) the size of river herring, (2) the concentration of river herring with respect to the target species, and (3) the yearly contribution of different fishery areas to the total catch of river herring. We divided the fishery's spatial range into four nearshore areas and tested two null hypotheses: (1) length frequency distributions of river herring are similar between areas and between species and (2) bycatch ratios are similar among areas. We also used length frequency distributions and river herring size at maturity to infer and compare maturity status. Results showed interannual, interspecies, and intraspecies differences in bycatch among and within the four nearshore areas. Bycatch in the northern areas was mainly migratory mature or near-mature river herring from mixed origins, whereas bycatch in the southern areas was a mix of juveniles, prespawning adults from nearby areas, and migratory adults. At the levels seen in 2011 and 2012, bycatch in the midwater trawl fishery could not account for the overall decline in river herring. However, a large proportion of river herring caught in the southern areas of the fishery may be juveniles originating from New Jersey to southern New England. To better understand this impact, continued monitoring and studies examining the at-sea population dynamics of river herring are needed.Received June 4, 2013; accepted April 2, 2014. © 2014 © American Fisheries Society 2014.