Growth, age estimation and feeding of captive Sevengill Sharks, Notorynchus cepedianus, at the Monterey Bay Aquarium

1992 ◽  
Vol 43 (1) ◽  
pp. 297 ◽  
Author(s):  
G Van Dykhuizen ◽  
HF Mollet
Keyword(s):  
Food Consumption ◽  
Sexual Maturity ◽  
Feeding Habits ◽  
Cube Root ◽  
Total Efficiency ◽  
Root Weight ◽  
Von Bertalanffy ◽  
Single Male ◽  
In Captivity ◽  
Size At Birth

Five methods, all based on the von Bertalanffy growth function (VBGF) model, were used with captive sevengills to characterize growth and to estimate both age and age at sexual maturity. Fabens' method (MI) gave a high k = 0.25 � 0.04 year-1 and a low L∞= 202 � 13 cm and W∞ = 41 � 11 kg. Determination of the third VBGF parameter, L0 or W0, requires age to be known. Reported estimates of size at birth were used to estimate ages of individual sharks. For the 'individual VBGF fit' method (M2), the age axis was fixed by using size at birth. For the 'derivative' method (M3), a growth rate was calculated from observed size when the sharks were received and size at birth. The results of either method confirmed that two sharks were first-year class and three sharks were second-year class when they were received. Both M2 and M3 required the use of a combination of total length (TL) and weight data via the 'TL-scaled cube root weight' method (M4) to obtain adequate statistics for individual sharks. The 'exponential regression' method (M5) was used to predict the sizes and ages of larger and older sharks. Age at sexual maturity for males was estimated by using L∞ = 225-250 cm and k = 0.174 to 0.132 year-1, which gave 4.3 to 5 years, in good agreement with the age estimated from clasper-length measurements from a single male. Age at sexual maturity for females was estimated by using L∞ = 275-300 cm and k = 0.107 to 0.090 year-1, which gave 11-21 years. Feeding habits have been monitored for captive sevengill sharks since 1985. Pups consumed up to 2% of their body weight (BW) per day, juveniles about 0.6% BW day-1, and adults about 0.2% BW day-1. Food consumption and, more importantly, total efficiency changed with age. The observed large food consumption and the observed high total efficiency of pups could be substantiated on the basis of a theoretical calculation of food intake based on von Bertalanffy growth. Adult sevengills showed a 'feast or famine' feeding pattern that followed a cycle of 5-7 days and that may have been influenced by water temperature and previous meal size. We conclude that growth rates in captivity and in the field are similar, based on the available growth data and feeding behaviour of sevengills in captivity and in the field.

Observations on the breeding and growth of the marsupial Perameles nasuta Geoffroy, with notes on other bandicoots.

1964 ◽  
Vol 12 (3) ◽  
pp. 322 ◽  
Author(s):  
AG Lyne
Keyword(s):  
Body Weight ◽  
Sexual Maturity ◽  
The Body ◽  
Cube Root ◽  
Single Individual ◽  
Age Changes ◽  
Breeding Activity ◽  
In Captivity ◽  
The Mean ◽  
The Right

A study has been made of 521 bandicoots (Perameles nasuta, 324; P. gunnii, 111 ; Isoodon obesulus, 86). Near Sydney, P. nasuta breeds all the year round with no indication of any peaks of breeding activity. Limited observations on P. gunnii and I. obesulus in Tasmania also suggest that births occur in every season of the year. Parturition of a single individual of P. nasuta was witnessed. Fifteen new-born specimens of this species were measured and body weight records were obtained for five of them. The average dimensions of these specimens, and consecutive measurements of three specimens born in captivity and of known age, were used to age pouch young of unknown age. Age changes in the appearance of P. nasuta are described and illustrated. Hair emerges on the trunk at about 40 days after birth and at 2 months the coat is similar to that of the adult. The rate of body growth is extremely rapid just prior to the opening of the eyes (usually at 45-48 days), and the young first appear outside the pouch several days later. The pouch contains eight teats, and the mean litter sizes were: P. nasuta, 2.44 (52 litters); P. gunnii, 2.23 (22 litters); I. obesulus, 2.33 (9 litters). In 47 litters of P. nasuta, 73 young were on teats of the left side compared with 46 on the right side of the pouch. The sexes were equally represented in the pouch young of the three species examined. In P. nasuta, sexual maturity is reached at about 450 g in females and about 650 g in males. The linear equivalence (cube root of the body weight) is used as an overall measure of size with which the parts of the body are compared.

X.—On the Feeding Mechanism of a Mysid Crustacean, Hemimysis Lamornæ

1927 ◽  
Vol 55 (1) ◽  
pp. 219-253 ◽  
Author(s):  
H. Graham Cannon ◽  
S. M. Manton
Keyword(s):  
Digestive System ◽  
Feeding Habits ◽  
Great Length ◽  
Gastric Mill ◽  
General Biology ◽  
Feeding Mechanism ◽  
In Captivity ◽  
Fish Tanks

The general biology of the Mysids has recently been studied at great length by Blegvad (1922) at Copenhagen. His paper, containing a very complete literature list, deals with Mysis inermis, Rathke, Mysis flexuosa, Müller, and Mysis neglecta, Sars. His comments on feeding are limited, and refer chiefly to the nature of the food that the animals ate in captivity. Gelderd's work (1909) on the digestive system of the Schizopoda describes the course taken by the food through the gastric mill, the masticatory functions of this apparatus, and the method by which the masticated food and digestive juices are brought together, but does not deal with the manner in which the food reaches the stomach. An account, then, of the method by which a mysid collects its food would fill a gap in our knowledge of these forms. The only description, as far as we are aware, of the feeding habits of a mysid is that of Depdolla (1923), who worked on Praunus [Mysis] flexuosus, but his account is superficial and in our opinion very inaccurate. The following paper deals with the feeding habits of a small mysid, Hemimysis lamornœ, about 8 mm. long, which has established itself in the larger fish-tanks at the M.B.A. laboratory at Plymouth. It breeds freely all the year round, and can be obtained from the tanks in abundance, although it is stated to be only a rare visitor in the Plymouth district.

A generic model to estimate food consumption: linking von Bertalanffy’s growth model with Beverton and Holt’s and Ivlev’s concepts of net conversion efficiency

2009 ◽  
Vol 66 (4) ◽  
pp. 683-700 ◽  
Author(s):  
Axel Temming ◽  
Jens P. Herrmann
Keyword(s):  
Food Consumption ◽  
Growth Model ◽  
Conversion Efficiency ◽  
Gadus Morhua ◽  
Generic Model ◽  
Similar Degree ◽  
Growth Equation ◽  
Von Bertalanffy ◽  
Gastric Evacuation ◽  
Consumption Rates

In this paper, a mathematical derivation is presented that links von Bertalanffy’s growth model with the concept of net conversion efficiency of Beverton and Holt, aiming at the development of an equation that can calculate food consumption rates of wild populations from parameters of the von Bertalanffy growth equation and an estimate of the net food conversion efficiency of Beverton and Holt. The derivation is based on Pauly’s version of the generalized von Bertalanffy equation, which allows the allometric exponent of the anabolism term to differ from 2/3, as in the standard von Bertalanffy equation. As a side product, a general model is formulated that describes the gross growth conversion efficiency (K1 of Ivlev) as a function of weight of the organism. The new equations for the estimation of food consumption are applied in two case studies, North Sea cod ( Gadus morhua ) and whiting ( Merlangius merlangus ), for which a variety of consumption estimates is available from conventional gastric evacuation-based methods. The new method produces results that show a similar degree of variability as was observed in various applications of the gastric evacuation method.

Intrapopulation variation in the diet of franciscana dolphin (Pontoporia blainvillei) off southern Brazil

2021 ◽  
pp. 1-17
Author(s):  
Manuela Bassoi ◽  
Eduardo R. Secchi ◽  
Daniel Danilewicz ◽  
Ignacio B. Moreno ◽  
Roberta A. Santos ◽  
...  
Keyword(s):  
Sexual Maturity ◽  
Linear Models ◽  
Prey Species ◽  
Prey Availability ◽  
Prey Selection ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Brazilian Coast ◽  
Pontoporia Blainvillei ◽  
Franciscana Dolphin

Abstract The franciscana dolphin (Pontoporia blainvillei) is a coastal dolphin endemic to the western South Atlantic Ocean. The dolphin is listed as vulnerable in the IUCN Red List, with incidental catches in gillnet fisheries the greatest conservation concern for this species. Insights into the feeding habits of this dolphin are essential to understand its distribution, movements and use of habitat, which are fundamental for effective management of the species. The feeding habits of franciscana dolphins were investigated from analyses of stomach contents of animals incidentally caught by two fishing operations from southern and northern regions of the southern Brazilian coast. In this study we investigate the existence of intrapopulation (sexual maturity and sex-related) variation in the diet of the franciscana dolphin, evaluating the spatial (northern and southern geographic areas) and seasonal influences. The analyses were based on Linear and Generalized Linear Models (LM and GLM). The majority of identified prey species were bottom-dwelling teleosts and the squid Doryteuthis sanpaulensis. The most important prey differed spatially and seasonally between northern and southern regions of the study area, and our results revealed significant differences between sexes and sexual maturity stages, mainly related to prey species sizes. This variation might indicate differences in prey selection, availability or habitat use patterns among these groups. In any case, these dietary differences are likely to minimize intraspecific competition for food resources, and/or indicate spatio-temporal variation in prey availability.

Reproductive hormone monitoring of dugongs in captivity: Detecting the onset of sexual maturity in a cryptic marine mammal

2013 ◽  
Vol 140 (3-4) ◽  
pp. 255-267 ◽  
Author(s):  
Elizabeth A. Burgess ◽  
Wendy H. Blanshard ◽  
Andrew D. Barnes ◽  
Sam Gilchrist ◽  
Tamara Keeley ◽  
...  
Keyword(s):  
Marine Mammal ◽  
Sexual Maturity ◽  
Reproductive Hormone ◽  
In Captivity

Reproductive biology of the pelagic stingray, Pteroplatytrygon violacea (Bonaparte, 1832), in the equatorial and south-western Atlantic Ocean

2014 ◽  
Vol 65 (11) ◽  
pp. 1035 ◽  
Author(s):  
D. P. Veras ◽  
F. H. V. Hazin ◽  
I. S. L. Branco ◽  
M. T. Tolotti ◽  
G. H. Burgess
Keyword(s):  
Sex Ratio ◽  
Atlantic Ocean ◽  
Reproductive Biology ◽  
Sexual Maturity ◽  
Pregnant Female ◽  
Longline Fishery ◽  
Western Atlantic ◽  
Pregnant Females ◽  
Size At Birth ◽  
Tuna Longline

From October 2005 to March 2010, a total of 480 pelagic stingray, Pteroplatytrygon violacea, specimens, 188 females and 292 males (0.64 female : 1 male), were taken in the equatorial and south-western Atlantic by the commercial tuna longline fishery and their reproductive biology was studied. Disc widths (DW) ranged from 28.0 to 66.0 cm for females and from 34.0 to 59.6 cm for males. Size at first sexual maturity was estimated at ~48.0 cm DW (first pregnant female) for females and ~41.0 cm DW for males. Ovarian fecundity, considering only follicles larger than 0.5 cm in diameter, ranged from 1 to 17 follicles per female, while the uterine fecundity of embryos in pregnant females in Stages 2 and 3 ranged from 1 to 5 embryos per female. The sex ratio between the embryos was almost equal (1.08 female : 1 male) and the size at birth was 19.0 cm DW.

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