Minimum Carapace Length Research Articles

The weight-length relationship and condition factor of the spiny lobster Panulirus penicillatus (Olivier, 1791) in the red sea coast

The objective of the present study was to establish the total weight (W)-carapace length (CL) relationship and condition factor (Cf) of the spiny lobster Panulirus penicillatus (Olivier, 1791) in the Sudanese Red Sea coast. Sixty specimens were used in the study. The male: female ratio was 1: 1.63. The minimum, maximum, and mean CL of male, female, and mixed male/female lobsters were (4.5-13.7, 8.34 cm), (4.2-12.3, 7.95 cm) and (4.2-13.7, 8.1 cm) consecutively. The corresponding W were (136-995, 488 gm), (170-1243, 456 gm) and (136-1243, 468.17 gm). The “b” values of the power regression of W vs. CL were 2.118, 2.281, and 2.208 for male, female, and mixed male/female lobsters in order, indicating negative allometric growth. Cf based on W and CL was 0.0837, 0.0865 and 0.0854 for male, female, and mixed male/female lobsters. The regression of Cf vs CL indicated that Cf decreased during growth. The study concluded that Sudan Red Sea coast water is conducive for lobster growth.

Growth Performance of Scalloped Spiny Lobster <i>Panulirus homarus</i> (Linaeus) Fed Formulated Diet in Recirculating System

Lobster aquaculture industry in sea cage farming has used seafood as its food leading to challenges such as disease risk, environmental degradation and disaster. This paper presents growth, survival, sexual maturity and flesh quality of scalloped spiny lobsters from a two period culture in recirculating system. In the first period, a number of 2655 healthy juveniles acclimated with formulated diet at average body weight of 11.4-14.0 g were stocked at 36.88 individuals m^-2 in three months. In the second period, a number of 2334 selected healthy juveniles at average body weight of 52.18-69.97 g were restocked at 13.5-14.1 individuals m^-2. The lobsters were fed formulated diet twice a day at a feeding rate of 2.2-1.6% of the body weight. The quality of biofilter based reused water was 28.4-29.8°C, pH: 7.6-8.0, salinity: 26.8-36.4 ppt, dissolved oxygen ≥ 5.2 mg L^-1, total ammonia nitrogen ≤ 0.82 mg L^-1, NO₂-N ≤ 0.5 mg L^-1, NO₃-N ≤ 4.3 mg L^-1, alkalinity: 96.4-132.4 mg L^-1. The body weight of lobsters increased following a polynomial (r² = 99.9%) and reached harvest size of 300 g after nine months and final size of 349.5 ± 9.9 g, survival of 81.5% and productivity of 4.51 ± 0.28 kg m^-2 after thirteen months. The lobster performance was similar to those fed seafood in sea cage farming. The berried females were observed at a minimum carapace length of 3.5 cm from July to September. The cooked lobster flesh and its content of fat and highly unsaturated fatty acids were less reddish and half of the lobsters fed seafood in sea cage farming, respectively. The differences are likely due to a deficiency of astaxanthin content in the formulated feed and possibly a poor assimilation of lipid by the lobsters. The results are interesting in development of a land based farming of spiny lobsters.

Life history and physical observations of primary burrowing crayfish (Decapoda: Cambaridae) Cambarus (Lacunicambarus) diogenes and Cambarus (Tubericambarus) polychromatus

Primary burrowing crayfish make up 15% of total crayfish species, but account for 32% of those imperiled. Primary burrowers are also much less studied as compared to secondary and tertiary burrowers. The purpose of this study was to observe the annual life cycles, and morphometric and morphological characteristics of two primary burrowing crayfish species: Cambarus (Lacunicambarus) diogenes Girard, 1852 and C. (Tubericambarus) polychromatus Thoma et al., 2005. Sampling occurred adjacent to two streams near Troy, AL, using hand excavation at one-month intervals from February 2011 to March 2012. A total of 195 C. diogenes (sex ratio = 1.3) and 194 C. polychromatus (sex ratio = 0.85) were collected. For a given size, C. diogenes had a broader carapace than C. polychromatus ( p< 0.001), and males had larger chelae than females for both species (p = 0.01 and p = 0.001, respectively). Minimum carapace length at sexual maturity (smallest form I) was 32.7 mm for C. diogenes males, 41.2 mm for C. diogenes females, 27.4 mm for C. polychromatus males, and 32.2 for C. polychromatus females. The proportion of form I males for both species increased in summer and remained at an increased level through winter, though C. polychromatus males remained reproductively active longer than C. diogenes. Females of both species were reproductively active only in winter except for one form I C. polychromatus female. Four ovigerous C. diogenes and three ovigerous C. polychromatus were collected in March, and five young of the year of C. polychromatus were found in burrows in June, July, and September.

Reproductive Biology of Portunus pelagicus in a South-East Australian Estuary

Abstract Portunus pelagicus (blue swimmer crab) is widely distributed and fished throughout the indo-west Pacific, but little is known of its biology and ecology in southeast Australia. In this study, the reproductive biology of P. pelagicus inhabiting Wallis Lake, a large coastal lake that supports the largest regional commercial fishery for the species was investigated. Males and females with mature gonads occur throughout the fishing season (November to July), however, ovigerous females are most prevalent in November and December. The mean size at which 50% of females reached maturity is estimated at 46 mm carapace length (CL). Fecundity increased linearly with CL and females are capable of producing up to 3 broods of eggs within the observed spawning season, with crabs of 60-69 mm CL producing approximately 76% of the estimated total egg production. Increasing the current minimum carapace length above 60 mm CL would potentially provide greater protection to mature females and increase total egg produc...

Population Assessment of the Pacific Green Spiny Lobster Panulirus gracilis in Pacific Panama

Populations of the green spiny lobster Panulirus gracilis (Streets 1871) have sustained increasing harvesting pressure in Pacific Panama for decades, but basic information about their biology and ecology in the region is scarce. This study provides baseline data for the densities and biometrics of P. gracilis in Las Perlas and Coiba Archipelagos. The number of surveyed lobsters in both archipelagos was surprisingly low (85 in Las Perlas and 67 in Coiba), and average densities were dismal (4.1 ± 8.8 ind. ha−1 and 5.3 ± 7.6 ind. ha−1, respectively). Saboga and San Jose Islands had the highest relative densities of P. gracilis in Las Perlas, whereas intermediate relative densities were found only on Coiba Island in the Coiba Archipelago. Lobster density was not associated with either substrate or depth. In Las Perlas, female carapace length (CL) was 40–95 mm and that of males was 25–100 mm; in Coiba, female CL was 45–124 mm and male CL was 45–121 mm. In Las Perlas, the smallest lobster with eggs had a CL = 65 mm and a tail length (TL) = 120 mm, whereas the smallest in Coiba had a CL = 60 mm and a TL = 81–115 mm. We recommend implementing: (1) the minimum capture CL as the average carapace length at which half of the lobster population from Coiba is adult (CL = 84 mm; TL = 112–155 mm); (2) a fishing season no longer than 6 mo; (3) management decisions involving local fishermen and native peoples; (4) marine reserves or no-take areas (NTA); and (5) long-term monitoring plans, as the best current options to insure the survival of P. gracilis in the region.

Reproduction and Nesting of the Endangered Ringed Map Turtle, Graptemys oculifera, in Mississippi

Reproduction and nesting in the ringed map turtle (Graptemys oculifera) were investigated in the Pearl River of west-central Mississippi in 1995 and 1996. Nesting occurred from mid-May until mid-July but peaked in mid-June. Minimum carapace length of females at sexual maturity was 130 mm, but mean size at maturity was between 130 and 140 mm. Mean and modal CSs were 3.7 and 3. Larger females were gravid earlier than smaller ones and both egg and CS declined as the nesting season progressed. CS was positively correlated with both female carapace length and body mass. Mean egg length, width, and mass were 38.8 mm, 22.7 mm, and 11.8 g, respectively. Hatchlings averaged 35.5 mm carapace length and 8.9 g in mass. Annual clutch frequency may range from 0.96 to 1.42, and a minimum of ca. 60% of females reproduced on an annual basis. Predators destroyed an average of 86% of nests each year. Major vertebrate nest predators were armadillos, raccoons, and fish crows. Invertebrate egg predators destroyed an additional 24% of eggs known to be fertile.

CARIDEAN SHRIMPS ASSOCIATED WITH THE SLIMY SEA PLUME (PSEUDOPTEROGORGIA AMERICANA) IN MIDSUMMER AT GUANA ISLAND, BRITISH VIRGIN ISLANDS, WEST INDIES

ABSTRACT Fifty-one slimy sea plumes (Pseudopterogorgia americana Gmelin, 1791) were sampled for caridean shrimps at Guana Island, British Virgin Islands, during one week in July 1992. Sampling depth ranged from 3-22 m. Nine species were collected: Hippolyte nicholsoni Chace, 1972; Latreutes sp.; Neopontonides chacei Heard, 1986; Perclimenes cf. patae Heard and Spotte, 1991; Periclimenes cf. pauper Holthuis, 1951; Periclimenes sp.; Pseudocoutierea antillensis Chace, 1972; Tozeuma cf. cornutum Milne Edwards, 1881; and Trachycaris rugosa (Bate, 1888). A total of 1,418 specimens (including fragments) was obtained. The number of shrimp species per gorgonian ranged from 1-5; one gorgonian harbored 156 shrimps. The 2 predominant species, N. chacei and H. nicholsoni, occupy different mean depths (12.6 and 8.2 m, respectively). Sexual dimorphism assessed with Mann-Whitney U-tests was not apparent in the specimens of N. chacei (P > 0.05), but females of H. nicholsoni were significantly larger than males (P < 0.001). Minimum carapace length (CL, the tip of the rostrum to the posterior dorsal margin of the carapace) at which male N. chacei acquire a single appendix masculina spine is 1.25 mm; male H. nicholsoni can acquire a single spine at 0.9 mm CL. Histological sections of male N. chacei showed that shrimp with 0 or 1 spine are least likely to be mature. Female N. chacei can become ovigerous at 1.9 mm CL and female H. nicholsoni at 1.2 mm CL. The taxonomic status of 5 of the 9 species collected is uncertain.

Body size, age distribution, and reproduction in a northern population of wood turtles (Clemmys insculpta)

A population of the wood turtle (Clemmys insculpta) was studied on the east side of Algonquin Provincial Park, Ontario, from 1987 to 1990. A total of 77 adults (56 females, 21 males) and 13 juveniles were captured, measured, and individually marked. Age at maturity was 17–18 years at a minimum carapace length of 185 mm for females and 199 mm for males. Our data supported the hypothesis that turtles in northern populations are larger and older at maturity than are those in southern populations. For 21 nests, mean clutch size was 8.8 eggs and egg mass was 96 g. Predators destroyed 15 of 17 nests in 1990, and had injured 60% of adult turtles observed. Therefore, our population had low recruitment, few juveniles, and high levels of predation on nests and adults. Comparisons among females refuted two predictions from optimal egg size theory. Mean width and mass, but not length, of eggs correlated positively with female size, and correlated positively with clutch size, even after effects of body size were removed by partial correlation. However, smaller females in the population had relatively longer eggs than did larger females, whereas the Algonquin females have absolutely smaller eggs than do much smaller females in a New Jersey population.

Effect of Assumptions about the Stock–Recruitment Relationship on a Lobster (Homarus gammarus) Stock Assessment

Stock assessment of the European lobster (Homarus gammarus) has involved yield per recruit analysis based on the established length cohort methodology of Jones (1974. ICES C.M. 1974/F:33; 1981. FAO Fish. Circ. 734) which assumes that recruitment to the fishery is independent of spawning stock. The Shepherd (1982. J. Cons. Int. Explor. Mer 40: 67–75) model has been used to simulate a range of assumed stock–recruitment relationships, and the resulting sensitivity analysis describes how these affect the relation between yield or biomass and four management variables, namely fishing mortality, minimum carapace length, maximum carapace length, and the capture or noncapture of egg-bearing females. Yield curves show a clear maximum with a marked tendency to stock collapse when fishing effort is high. For the range of simulations considered, the probability of an early recruit failure is greatest for asymptotic stock–recruitment curves, which generate yield curves with maxima at an effort substantially lower than the present level. Only with a highly overcompensatory stock–recruitment curve is there a case for increasing effort to maximise yield, but such a relationship tends to reduce the benefit of increasing minimum carapace length or of setting a maximum carapace length. The model predicts that the assumption made about the stock–recruitment relationship also has a marked effect on the results expected from a ban on the landing of egg-bearing females. Overall the results confirm the unsatisfactory prognosis of the yield per recruit model and emphasise the need to gain an understanding of the biological factors determining the shape of the lobster stock–recruitment curve.

Variation in the Male Reproductive Cycle in a Population of Stinkpot Turtles, Sternotherus odoratus, from Virginia

Annual variation in the testicular cycle of a population of stinkpot turtles, Sternotherus odoratus, from Virginia was found to occur in late stages of spermatogenesis but not in initiation of the cellular cycle or in the testis weight cycle. Seasonal variation in testis weight was generally concordant with variation in the spermatogenic cycle and followed the typical postnuptial pattern in which testicular growth and recrudescence begins in late spring, followed by peak weights and spermiogenesis in August, and regression in fall and winter. Minimum testis weights and onset of spermatogenesis were in May. The variables seminiferous tubule diameter, carapace length, and month accounted for 89.3% of the variation in testis weight; year accounted for 0.1%. Males in this population matured at the end of their second year at a minimum carapace length of 51 mm. Geographic variation in timing of spermatogenic events is discussed with reference to populations in Alabama and Michigan. Water temperature is the probable cue for initiation of spermatogenesis in stinkpots, and the variation in occurrence of later stages may be due to individual movement in the water column. Comparisons are made with the testicular cycle of a syntopic population of painted turtles, Chrysemys picta, studied concurrently.