Influence of settlement time and size on postsettlement growth in the American lobster (Homarus americanus)

We investigated the size and timing of settlement of postlarval (fourth instar) American lobster (Homarus americanus) and the size attained by the end of the first growing season. Mean size and duration of benthic instars (IV-XI) were obtained from a field growth experiment. Lobsters settling in early- and mid-season were larger at each instar and had different growth profiles than late-season settlers. In particular, the rate of growth at the fifth and sixth instar transition was greater for early- and mid-season settlers than for late-season settlers. Postlarvae settling early reached the ninth instar sooner than mid- or late-season settlers. Estimates of size and intermolt duration of each instar for early- and late-season postlarvae were applied to planktonic postlarval data (1988-1995) to estimate growth trajectories during the first year. For all years, postlarvae present early in the season were 30-50% larger (carapace length) and two or three instars further developed than late settlers by the end of the growing season. Estimates of size attained by the end of the 1994 growing season matched field-collected benthic size frequency data for this same year. Although initial carapace length at settlement was important, the timing of settlement was more influential on the size attained by the end of the first growing season.

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The Growth Rate of the American Lobster (Homarus americanus)

Journal of the Fisheries Research Board of Canada ◽

10.1139/f53-024 ◽

1953 ◽

Vol 10 (7) ◽

pp. 371-412 ◽

Cited By ~ 48

Author(s):

D. G. Wilder

Keyword(s):

Carapace Length ◽

Growing Season ◽

Homarus Americanus ◽

American Lobster ◽

Maritime Provinces ◽

Larval Stages ◽

Total Length ◽

Straight Line ◽

Size Groups ◽

Stage 1

Carapace measurements of lobster larvae caught in the western part of Northumberland Strait showed that in this area the natural growth in length per moult is 34.4 per cent from stage 1 to stage 2, 31.8 per cent from stage 2 to 3, and 30.3 per cent from stage 3 to 4. The seasonal distribution of the first four larval stages was determined from plankton tows made continuously from mid-June to late September each year from 1948 to 1952. To determine natural annual growth, lobsters of 15 to 25 cm., total length, were sorted into five or six size groups and were distinctively marked by means of holes punched through the tail fan. These were liberated on six widely separated fishing grounds in the Maritime Provinces. Recoveries of these marked lobsters four to twelve months after release showed that in the southern Gulf of St. Lawrence, 15- to 20-cm. lobsters grew 8 to 9 mm. (13 to 15 per cent) in carapace length, 22 to 25 mm. (13 to 14 per cent) in total length and 80 to 95 grams (45 to 53 per cent) in weight. In southern Nova Scotia and Grand Manan 20- to 25-cm. lobsters grew 10 to 12 mm. (13 to 15 per cent) in carapace length, 27 to 34 mm. (12 to 15 per cent) in total length and 170 to 220 grams (43 to 54 per cent) in weight. From the carapace length of 4th-stage larvae and straight-line equations relating carapace length before moulting and carapace length after moulting, the average carapace lengths of lobsters in stages 5 to 20 were calculated. From observations and calculations on the growth per moult and moulting frequency, it is estimated that in the Northumberland Strait area lobsters reach a length of 14 cm. (51/2 in.) at the end of the fifth growing season (41/4 years old) and 24 cm. (91/2 in.) at the end of the ninth growing season (81/4 years).

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Intermolt Insemination, an Alternative Mating Strategy for the American Lobster (Homarus americanus)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f90-267 ◽

1990 ◽

Vol 47 (12) ◽

pp. 2402-2406 ◽

Cited By ~ 24

Author(s):

S. L. Waddy ◽

D. E. Aiken

Keyword(s):

Reproductive Strategy ◽

Carapace Length ◽

Homarus Americanus ◽

Mating Strategy ◽

American Lobster ◽

Male Aggression ◽

Female Receptivity ◽

Molt Stage ◽

Alternative Mating Strategy ◽

Ovarian Stage

American lobster (Homarus americanus) have a dual mating strategy. Although most females mate when they are newly molted, mating can occur at any molt stage if necessary, in the laboratory, virtually all uninseminated preovigerous females mate prior to spawning. Male aggression is a major factor in the success of intermolt mating and males can discriminate between immature and mature females, and between inseminated and uninseminated females. Female receptivity is affected by both ovarian stage and the presence of stored sperm, but not by molt stage. Most females become unreceptive after insemination, but their receptivity returns once the supply of stored sperm is exhausted. Intermolt mating occurs in smaller lobster that for some reason did not mate at molt, and it is an important part of the reproductive strategy of larger lobster. Lobster s[Formula: see text] carapace length frequently spawn twice without molting and often fail to store sufficient sperm to fertilize consecutive spawnings. Intermolt mating ensures these females will produce fertile second broods.

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The effect of cooking and freezing on the carapace length of the American lobster, Homarus americanus H. Milne Edwards, 1837

Crustaceana ◽

10.1163/156854003322381531 ◽

2003 ◽

Vol 76 (6) ◽

pp. 741-748

Author(s):

Manon Mallet

Keyword(s):

Carapace Length ◽

Homarus Americanus ◽

American Lobster

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Sexual differentiation in juvenile American lobster (Homarus americanus)

Canadian Journal of Zoology ◽

10.1139/cjz-2018-0297 ◽

2019 ◽

Vol 97 (7) ◽

pp. 650-653

Author(s):

Michel Comeau ◽

Kadra Benhalima

Keyword(s):

Larval Stage ◽

Reproductive System ◽

Sexual Differentiation ◽

Carapace Length ◽

Homarus Americanus ◽

Male Reproductive System ◽

American Lobster ◽

Males And Females ◽

Pelagic Larval Stage

American lobsters (Homarus americanus H. Milne Edwards, 1837) settling to the bottom after their pelagic larval stage are sexually undifferentiated. Based on stereomicroscope observations, the female’s gonopore first appeared for lobsters about 13 mm carapace length (CL) and the dimorphism of the first pair of male pleopods was first observed at about 15 mm CL. Based on histological observations, the internal reproductive system for both males and females began differentiating at sizes ≥20 mm CL. The vasa deferentia were observed for males >30 mm CL indicating that the male reproductive system is fully formed. For females, the ovaries were observed at sizes ≥20 mm CL, but the oviducts were not detected in animals <36 mm CL. The male reproductive system is morphologically complete at a substantially smaller CL than for females.

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Hogpotato (Hoffmanseggia glauca) Control with Herbicides and Rotational Crop Response

Weed Technology ◽

10.1017/s0890037x00037490 ◽

1993 ◽

Vol 7 (3) ◽

pp. 650-656 ◽

Cited By ~ 2

Author(s):

R. Brent Westerman ◽

Don S. Murray ◽

Eric P. Castner

Keyword(s):

Field Experiments ◽

Growing Season ◽

First Year ◽

Crop Response ◽

Sensitive Species ◽

Crop Species ◽

Late Season ◽

Rotational Crop ◽

Herbicide Activity ◽

Residual Herbicide

Three field experiments were conducted in 1987 through 1989 to evaluate hogpotato control and rotational crop response resulting from applications of five herbicides. At the end of the first year, triclopyr and imazapyr controlled hogpotato late-season as high as 87 and 94%, respectively. Following a sequential application in 1988, triclopyr and imazapyr controlled 94 and 100% of hogpotato, respectively, during the 1989 growing season. Hogpotato biomass, collected at the termination of the experiments, was reduced by all treatments at all locations except at Altus where dicamba was applied in 1987 followed by a spot application of glyphosate in 1988. Soils from these experiments were bioassayed for residual herbicide activity using three potential rotational crop species. Tebuthiuron and imazapyr caused the greatest biomass reductions with cotton and wheat being the most sensitive species to these herbicides.

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Growth of juvenile American lobster Homarus americanus in a changing environment

Marine Ecology Progress Series ◽

10.3354/meps11854 ◽

2016 ◽

Vol 557 ◽

pp. 177-187 ◽

Cited By ~ 8

Author(s):

MD McMahan ◽

DF Cowan ◽

Y Chen ◽

GD Sherwood ◽

JH Grabowski

Keyword(s):

Homarus Americanus ◽

American Lobster ◽

Changing Environment

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Predicting bycatch hotspots based on suitable habitat derived from fishery-independent data

Marine Ecology Progress Series ◽

10.3354/meps13302 ◽

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.

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