Squid Diet Research Articles

Validation of the Use of Tritiated Water, Doubly Labeled Water, and 22Na for Estimating Food, Energy, and Water Intake in Little Penguins, Eudyptula minor

The water, sodium, and energy turnovers of little penguins were examined by comparing estimates determined from tritium (HTO), sodium-22 (22Na), and doubly labeled water (DLW) turnovers with estimates frotm simultaneous materials balance trials. Two diets were used to assess the effect of food type on assimilation eficiencies and on turnover rates. Energy assimilation eficiencies were higher with the squid diet than with the fish diet but were still the lowest recorded for any penguin species. All three isotopes had equilibrated with body pools between 2 and 6 h after injection and biological half-lives were 4.3, 3.4, and 2.9 days for HTO, 18O, and 22Na, respectively, with no difference between diets. On average, HTO-derived estimates were significantly higher than measured intake (6.5%), but DL W-derived estimates of metabolic rate were not significantly different from materials balance estimates. On average, 22Na underestimated dietary sodium intake by 5. 0%, and, although this difference was not significant, discrepancies were greater with the squid diet than with the fish diet. Changes of approximately 50% in isotope levels in the blood are required between injection and sampling to ensure reliable results from turnovers of all three isotopes.

Metabolism of trimethylamines in kelp bass (Paralabrax clathratus) and marine and freshwater pink salmon (Oncorhynchus gorbuscha).

3H or 14C labeled tracers were used to investigate the metabolism of trimethylamine (TMA), trimethylamine oxide (TMAO), choline, and betaine in free swimming kelp bass (Paralabrax clathratus). An indwelling cannula in the ventral aorta was used to administer tracer and with-draw blood samples. The concentrations of TMA and TMAO were determined in liver, muscle, and plasma. The TMA liver content is higher than that of muscle (0.85 vs less than 0.01 mumoles/g wet tissue) while the amount of TMAO in muscle greatly exceeds its liver concentration (60 vs 0.04 mumoles/g wet tissue). Prolonged fasting (21 and 75 days) or feeding the fish a squid diet containing high levels of TMAO did not alter the tissue concentrations of TMA or TMAO, suggesting that these compounds are endogenous in origin and that their tissue concentrations are subject to regulation. Comparison of the radiospecific activities of TMA and TMAO, and the administered TMA tracer suggest that TMA is channeled directly to TMAO in the liver without equilibration in the hepatic TMA pool. The conversion kinetics of TMA to TMAO and the distribution of these amines in liver and muscle with time suggest that labeled TMA is rapidly taken up into a sequestered pool from which it is slowly released, oxidized to TMAO in the liver, and then transported via the circulation to the muscle mass. The location of this proposed sequestered TMA pool was not determined. Experiments with labeled choline and betaine suggest that these compounds are interconverted in the liver and that enzymes are present for conversion of choline in equilibrium betaine----TMA----TMAO. Labeled dimethylamine (DMA) was not metabolized and is, therefore, probably not a precursor of TMA and TMAO. [14C]Trimethylamine (TMA) was also used to investigate the possible role of trimethylamine oxide (TMAO) as an osmoregulatory compound in migrating prespawning cannulated Pacific pink salmon (Oncorhynchus gorbuscha) taken from marine or fresh water environments. Marine and fresh water salmon oxidized administered [14C]TMA to TMAO; labeled metabolites other than TMA and TMAO were not detected. Four hours after [14C]TMA injection about 10% of the administered dose was present in muscle as labeled TMAO and about 33% as TMA. Unlike our finding in kelp bass, [14C]TMAO was not recovered in liver, although low amounts of labeled TMA were found (0.4% of administered dose). Labeled TMA and TMAO, however, were detected in liver after [14C]betaine administration to a marine salmon, indicating that TMA-mono-oxygenase is present in salmon liver.(ABSTRACT TRUNCATED AT 400 WORDS)

Utilization Efficiency of a Squid Diet by Adult King Penguins (Aptenodytes patagonicus)

bution of penguins on the Antarctic Peninsula and islands of the Scotia Sea. Cambridge, England, Brit. Antarctic Surv. , D. M. ROOTES, & R. A. PRICE. 1981. Increases in penguin populations at Signy Island, South Orkney Islands. Brit. Antarctic Surv. Bull. 54: 4756. LERESCHE, R. E., & W. J. L. SLADEN. 1970. Establishment of pair and breeding site bounds by young known-age Adelie Penguins. Anim. Behav. 18: 517-526. SLADEN, W. J. L. 1958. The pygoscelid penguins. Sci. Rept. Falkland Islands Depend. Surv. 17: 1-97. , & R. E. LERESCHE. 1970. New and developing techniques in Antarctic ornithology. Pp. 585596 in Antarctic ecology (M. Holdgate, Ed.). London, Academic Press. TRIVELPIECE, W. Z., & N. J. VOLKMAN. 1979. Nestsite competition between Adelie and Chinstrap penguins: an ecological interpretation. Auk 96: 675-681. VOLKMAN, N. J., S. G. TRIVELPIECE, W. Z. TRIVELPIECE, & K. E. YOUNG. 1982. Comparative studies of pygoscelid penguins in Admiralty Bay. Antarctic J. U.S. 17: 180.

FEEDING PATTERNS OF THE LONG-FINNED SQUID,LOLIGO PEALEI, IN NEW ENGLAND WATERS

Gut content analyses have shown that the diet of the long-finned squid, Loligo pealei, differs between inshore spawning and nursery grounds and offshore winter grounds. In this study, squid were collected inshore from May through November in lower Narragansett Bay, Rhode Island and offshore during winter along the continental shelf between Cape Hatteras and Cap Cod. In both collections crustaceans were more frequently consumed than either fish or squid, but fish were eaten by a wider size range of squid and more frequently inshore. Prey-type selection based on size was common in both samples, but it is unlikely that the species composition is the same in both areas. These data suggest that L. pealei is a highly opportunistic predator, whose diet primarily reflects the local abundance of potential prey species. Such a flexible feeding strategy could account for the large spatial and temporal variations which have been reported in the diet of this squid from various offshore areas.

Energy, Nitrogen, and Electrolyte Flux and Sea Water Drinking in the Sea Otter Enhydra Lutris

An elevated metabolism requires the sea otter, Enhydra lutris, to include large quantities of invertebrate prey in its diet. This necessitates processing large quantities of energy, nitrogen, electrolytes, and water. Feeding studies were conducted to document these high material and energy fluxes and the dilution of tritiated water through time was used to measure total water flux. Total energy influx on a diet of clam and squid was 234 ± 19 (X ± SE) kcal/kg-day with an assimilation efficiency of 82% and an estimated metabolic efficiency of 72%. Material influx from food was 5.22 ± 0.41 (X ± SE) g/kg-day nitrogen and 166 meq/kg-day electrolytes (Cl, Na, K, Mg). The presence of large lobulate kidneys may allow for the production of large volumes of urine at elevated concentrations. Urine samples from wild and captive animals had a mean osmotic pressure of 1,627 ± 91 mOsm/kg (range, 910-2,130), which was composed of 647 meq/L Na, K, Cl and 698 ± 67 mmol/L urea. Total water flux was 269 ± 25 mL/kg-day. Mean ...

Mariculture potential of the spot prawn, Pandalus platyceros Brandt

Biological characteristics and culture methods were investigated for the spot prawn, Pandalus platyceros Brandt. Ovigerous adults were caught in the local fishery; six of these produced 2 628 to 4 669 larvae. The larval period ranged from 26 to 35 days (9.5–12.0°C). Maximum larval survival was about 70%, with mortalities being most frequent during ecdysis. The relation of wet weight (g) to carapace length (mm) for the first 26 months was calculated as log W = −3.0843 + 2.9308 log L. Prawns showed good survival between 9.5 and 21.0°C. Mortality increased sharply when temperatures exceeded 21.0°C. Salinities below 22‰ resulted in a sharp increase in mortality. A diet of brine shrimp nauplii sufficed for newly hatched larvae. Growth was enhanced when larvae were fed a unicellular algal supplement ( Phaeodactylum tricornutum), although mortality was somewhat higher. Larvae progressed rapidly to foraging on larger brine shrimp and diced foods. Six-month-old spot prawns raised on a squid diet averaged 3.4 g, and at 1 year the mean weight was 6.3 g. A feeding experiment, incorporating 12 diets, disclosed that highest growth rates and best food conversion ratios were achieved on a combined California seamussel and giant red sea urchin diet. However, the best growth rate achieved was considered marginal for mariculture. It was concluded that unless the growth rate could be accelerated by other food formulations or culture techniques, a monoculture system for mass cultivation would not be feasible. The spot prawn may have potential in a polyculture system.

Food of the squid,Loligo duvauceli d’Orbigny

Loligo duvauceli which contributes to the cephalopod fishery in India is a carnivorous like other cephalopod species. Its stomach contents are mainly the crustaceans, fish and squid. Mysiids, euphausiids and ostracods from bulk of the crustacean intake in the squid diet. Major items of food differ significantly from month to month. Fish always occurs in the diet of the squids of all sizes. The preference to crustacean meal declines with the increase in size and the squids above 80 mm in size are cannibals. Crustaceans are present in the squid stomach during four month period, October to January. The data indicate that the occurrence of empty stomachs is more common in female than in male squids. Normal feeding was noticed during the period January to May 1970, but the slackness in the feeding was evident in October–November 1969 during spawning period.