Does Eyestalk Ablation Accelerate Molting in the Lobster Homarus americanus?

1973 ◽  
Vol 30 (10) ◽  
pp. 1600-1603 ◽  
Author(s):  
Jeffrey B. Sochasky ◽  
D. E. Aiken ◽  
D. W. McLeese
Keyword(s):  
Carapace Length ◽  
Limb Regeneration ◽  
Homarus Americanus ◽  
Eyestalk Ablation

Contrary to published results obtained with larger Homarus americanus, bilateral eyestalk ablation induces precocious molting in lobsters about 60 mm carapace length. The observed "acceleration" appears to result from the prevention or termination of a D0 development plateau. However, limb regeneration in eyestalkless lobsters appears to be inhibited.

Determinants of Postmolt Size in the American Lobster (Homarus americanus). I. D13 is the Critical Stage

1993 ◽  
Vol 50 (10) ◽  
pp. 2106-2111 ◽  
Author(s):  
Jin-Hua Cheng ◽  
Ernest S. Chang
Keyword(s):  
Limb Regeneration ◽  
Homarus Americanus ◽  
American Lobster ◽  
Molt Cycle ◽  
Promoting Effect ◽  
Critical Stage ◽  
Eyestalk Ablation ◽  
Growth Promoting ◽  
Large Container

Juvenile American lobster (Homarus americanus) were subjected to induced limb autotomy, eyestalk ablation, and manipulation of container space at different molt stages to test the hypothesis that postmolt size is predetermined at the time of deposition of the epicuticle. Molt increments in autotomized animals that regenerated limbs were reduced by 30–40%. Molt increments were reduced by only 5–10% in autotomized animals that did not regenerate limbs. The critical stage for limb regeneration is D13. Depending on the time of limb autotomy, molt intervals were decreased (stages B–C), increased (stages D11 and D12), or not affected (stages D0, D13, D2, and D3). Eyestalk ablation shortened the molt interval; the change in molt interval was less when ablation was performed near the end of the current molt cycle. Eyestalk-ablated lobsters had larger molt increments compared with intact controls, especially in the chelipeds. This growth-promoting effect disappeared if ablation was conducted at or after D13. Transferring lobsters from small to large container spaces shortened molt intervals and increased molt increments. Increases in molt increments only occurred when transfers were made before D13. We conclude that postmolt size of lobsters is predetermined at D13 when the new epicuticle is produced.

Multiple Fertilization and Consecutive Spawning in Large American Lobsters, Homarus americanus

1986 ◽  
Vol 43 (11) ◽  
pp. 2291-2294 ◽  
Author(s):  
S. L. Waddy ◽  
D. E. Aiken
Keyword(s):  
Body Size ◽  
Carapace Length ◽  
Homarus Americanus ◽  
Large Female ◽  
Bay Of Fundy ◽  
Relative Fecundity ◽  
Logarithmic Relationship

Large female American lobsters, Homarus americanus (> 120 mm carapace length), maintained at nearshore Bay of Fundy temperatures often spawn twice without an intervening molt (consecutive spawning). Consecutive spawning occurs in two forms: successive-year (spawning in two successive summers, a molt in the first and fourth years) and alternate-year (spawning in alternate summers, a molt in the first and fifth years). In both types, females often are able to fertilize the two successive broods with the sperm from a single insemination (multiple fertilization). Twenty of 21 large females that were held for up to 13 yr displayed one of these types of consecutive spawning. Consecutive spawning and multiple fertilization enable large lobsters to spawn more frequently over the long term than their smaller counterparts. This, combined with the logarithmic relationship between body size and numbers of eggs produced, means that very large lobsters have a much greater relative fecundity than previously thought.

Size–Maturity Relationships and Related Observations in Newfoundland Populations of the Lobster (Homarus americanus)

1980 ◽  
Vol 37 (6) ◽  
pp. 945-956 ◽  
Author(s):  
G. P. Ennis
Keyword(s):  
Carapace Length ◽  
Size Range ◽  
Sex Ratios ◽  
Weight Ratio ◽  
Homarus Americanus ◽  
Spawning Season ◽  
Length Ratio ◽  
Maturity Indices

Female maturity ogives for five Newfoundland populations of the lobster (Homarus americanus) gave 50% maturities ranging from 71- to 76-mm carapace length. Sizes at which distinct inflections (indicating onset of maturity) and asymptotes (indicating 100% mature) are present in the abdomen width/carapace length ratio vs. carapace length relationships coincide with the smallest ovigerous and largest immature specimens, respectively, observed in those particular samples. Inflection in the crusher claw weight/whole weight ratio vs. carapace length relationships (used in this paper to indicate onset of maturity in males) occurred at larger sizes than inflections in the abdomen width/carapace length ratios of females.The percentage of nonovigerous females that spawn in a given year generally increases with increasing size. The highest percentage of nonovigerous females tagged with sphyrion tags prior to the spawning season that were ovigerous when recaptured 10–12 mo later was 83.8%. The percentage of ovigerous females with new shells (i.e. molted and spawned in same year) varied between areas and years and ranged from 0 to 38.5% of the total number of ovigerous females in fall samples. The percentage of ovigerous females in samples also varied between areas and years and ranged from 2.6 to 30.4% of the total number of females greater than the size at 50% maturity. In general a greater percentage of females was ovigerous at sizes between the size at 50% maturity and 80 mm (largest subcommercial size) than at commercial sizes.In a sample of nonovigerous females, the size range at which 50% were fertilized (76–80 mm) coincided closely with the size at 50% maturity (75 mm) for the area.At subcommercial sizes (< 81 mm) the sexes were approximately equally represented in fall trap-caught samples but females heavily outnumbered males in diver-caught samples taken over the same period. At commercial sizes, however, males heavily outnumbered females in the trap-caught samples while in diver-caught samples the sexes were equally represented.Key words: lobster (Homarus americanus), maturity ogives, maturity indices, percent ovigerous, sex ratios

Laboratory and Field Tests of Modified Sphyrion Tags on Lobsters (Homarus americanus)

1970 ◽  
Vol 27 (2) ◽  
pp. 257-264 ◽  
Author(s):  
D. J. Scarratt
Keyword(s):  
Carapace Length ◽  
Field Tests ◽  
Homarus Americanus ◽  
Poor Survival ◽  
Internal Organs ◽  
Fishing Season ◽  
Tag Loss

Mortalities of lobsters held in the laboratory and tagged with sphyrion tags inserted dorsally between the carapace and abdomen (subcarapace tag) and between the second and third abdominal segments (abdomen tag) did not differ significantly. Premoult tag loss was negligible. The subcarapace tag was retained significantly better through moulting.Returns of subcarapace-tagged and abdomen-tagged lobsters released on the fishing grounds in June, 11 weeks before the August 10 opening of the fishing season, were lower than returns of carapace-tagged lobsters released in early August. More subcarapace-tagged than abdomen-tagged lobsters were returned, and a higher proportion had moulted. Growth was comparable to that reported in the literature. Few lobsters were recaptured during the following fishing season, 14–16 months after liberation, and none subsequently. Returns from lobsters less than 63.5 mm carapace length (sublegal) when tagged were extremely low. Poor survival may be related in part to time of release. Some injury to internal organs may occur with both tags. The subcarapace tag is clearly superior but may be of limited value in the field for lobsters below 63.5 mm carapace length.

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

1990 ◽  
Vol 47 (12) ◽  
pp. 2402-2406 ◽  
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.

Growth of Tagged American Lobsters, Homarus americanus, in the Bay of Fundy

1983 ◽  
Vol 40 (10) ◽  
pp. 1667-1675 ◽  
Author(s):  
Alan Campbell
Keyword(s):  
Carapace Length ◽  
Growth Curves ◽  
Homarus Americanus ◽  
Multiple Regression Model ◽  
Growth Increment ◽  
Bay Of Fundy ◽  
Von Bertalanffy ◽  
Immature Female ◽  
Size Number ◽  
Empirical Growth

Sphyrion-tagged lobsters recaptured in the Bay of Fundy during 1977–80 yielded mean annual molt increment and molt probability data for male and female lobsters of 60–171 mm carapace length from which growth curves were calculated. In addition, a multiple regression model was used to generate growth curves from premolt size, number of molt periods lobsters were exposed to, and growth increment data for 850 tagged lobsters at liberty for 1–5 yr. Von Bertalanffy parameters were calculated from these empirical growth curves, which suggest that lobsters take 20–35 yr from time of hatching to reach 200 mm carapace length in the Bay of Fundy. Analysis of pleopods indicated that the majority of lobsters molt during August–October each year. Growth per molt of immature (60–94 mm carapace length) and mature (95–170 mm carapace length) male and immature female lobsters was arithmetic (regression slope 1.04) but was regressive for mature females (slope 0.95). Mature lobsters molted less frequently than immature lobsters, but mature males grew more rapidly than mature females. Most mature females in the Bay of Fundy are on a 2-yr molt–reproductive cycle. About 20% of ovigerous females recaptured within 2 yr after release had extruded eggs a second time without molting, confirming that multiple egg extrusions between molts do occur naturally.

Determinants of Postmolt Size in the American Lobster (Homarus americanus). II. Folding of Premolt Cuticle

1994 ◽  
Vol 51 (8) ◽  
pp. 1774-1779 ◽  
Author(s):  
Jin-Hua Cheng ◽  
Ernest S. Chang
Keyword(s):  
Homarus Americanus ◽  
Size Increase ◽  
American Lobster ◽  
Eyestalk Ablation ◽  
Before And After ◽  
Rearing Condition

The effects of eyestalk ablation, regeneration, and rearing condition on the size of new cuticles before and after expansion were studied in juvenile Homarus americanus. Both eyestalk-ablated and intact lobster grew larger in large spaces than in small spaces. In contrast, regeneration reduced molt increment. Despite large differences in molt increment (percentage of size increase during a molt) among experimental groups, the percentage of postmolt size increase that could be accounted for by unfolding of the new cuticle was large and constant in each group. In addition, transferring freshly molted lobster to dilute seawater did not produce any further size increase but instead caused cuticle breakage in some animals. We conclude that molt increment in lobster is determined by regulating the size of the cuticle before ecdysis. The size of the postmolt cuticle is primarily a result of unfolding of the new, previously folded cuticle.

The catchability of large American lobsters (Homarus americanus) from diving and trapping studies off Grand Manan Island, Canadian Maritimes

2006 ◽  
Vol 63 (9) ◽  
pp. 1925-1933 ◽  
Author(s):  
M J Tremblay ◽  
S J Smith ◽  
D A Robichaud ◽  
P Lawton
Keyword(s):  
Generalized Linear Models ◽  
Carapace Length ◽  
Linear Models ◽  
Size Range ◽  
Late Summer ◽  
Homarus Americanus ◽  
Agonistic Interactions ◽  
Size Groups ◽  
Early Fall ◽  
Catch Rates

Catchability (q) in traps was estimated for American lobsters (Homarus americanus) in Flagg Cove, off Grand Manan Island (New Brunswick, Canada), where large females (>100 mm carapace length (CL)) aggregate in late summer and early fall. In 2001 and 2002, diver surveys were used to estimate lobster density, and traps were then deployed to obtain catch rates. Bayesian generalized linear models were fit to the densities of different size groups (81–100, 101–130, 131–160, and >160 mm CL) of ovigerous females, non-ovigerous females, and males. Catchability was strongly affected by year. Differences in q due to sex and size for ovigerous females, non-ovigerous females, and males were apparent but were not consistent between years. Size was not an important factor for the catchability of lobsters between 81 and 160 mm CL. In comparison with lobsters of a similar size in other areas, Flagg Cove lobsters in the size range of 81–100 mm CL were less catchable. We hypothesize that this resulted from the high densities and larger sizes of lobsters in Flagg Cove, which likely lead to increased agonistic interactions and reduced entry of lobsters into traps.

Effects of eyestalk ablation upon water relations in the American lobster,Homarus americanus

1987 ◽  
Vol 244 (3) ◽  
pp. 389-393 ◽  
Author(s):  
Susan A. Jackson ◽  
Marilyn J. Bruce ◽  
Ernest S. Chang ◽  
James S. Clegg
Keyword(s):  
Water Relations ◽  
Homarus Americanus ◽  
American Lobster ◽  
Eyestalk Ablation

Movements of Tagged American Lobsters, Homarus americanus, off Southwestern Nova Scotia

1985 ◽  
Vol 42 (2) ◽  
pp. 229-238 ◽  
Author(s):  
Alan Campbell ◽  
Aivars B. Stasko
Keyword(s):  
Nova Scotia ◽  
Continental Shelf ◽  
Carapace Length ◽  
Gulf Of Maine ◽  
Homarus Americanus ◽  
Long Distance ◽  
Mature Adults ◽  
Straight Line ◽  
Straight Line Distance ◽  
Long Distance Movement

A total of 4304 American lobsters (Homarus americanus) were tagged and released in inshore areas off southwestern Nova Scotia and on northwest Browns Bank during June–August 1975. Of the 424 lobsters recaptured within 5.4 yr of release, 385 had known recapture locations. For all release areas the average straight-line distance traveled by mature ([Formula: see text]carapace length) lobsters (15.6 km) was significantly greater than for immature (59–94 mm carapace length) lobsters (4.7 km). Most (69.3%) of the immature lobsters (N = 212) were recaptured less than 18.5 km (10 naut mi) from the release sites; for mature lobsters (N = 173) this percentage was 40.5%. Previous tagging studies off southwestern Nova Scotia revealed little evidence of long-distance movement; our study, however, shows that mature lobsters can move long distances. Many (19.7%) of the mature lobsters were recaptured more than 92.6 km (50 naut mi) from the release sites. The overall direction of travel was south, in both an east and west direction, with many lobsters moving greater than 50 km from coastal Nova Scotia and Browns Bank into the Gulf of Maine and to the slopes of the continental shelf. Thirteen lobsters moved from Browns Bank to inshore areas of southwestern Nova Scotia. The evidence of the long-distance interchange of a portion of the mature adults between southwestern Nova Scotia and the adjoining continental shelf suggests that lobsters in these areas could belong to a single stock.

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