Estimation of growth and financial analysis through the application of Ipil ipil (Leucaena leucocephala) leaf meal as supplements to soybean and fish meal in the diet of juvenile monosex tilapia (Oreochromis niloticus)

Among plant protein ingredients,ipil ipil (Leucaena leucocephala) leafmeal (ILLM) is considered the most nutritive plant protein source after soybean meal in aquatic feeds. That was proven in a 21-day experiment conducted to assess the response of juvenile Monosex Nile tilapia Oreochromis niloticus with four iso-nitrogenous formulated diets: One control diet was formulated based on fishmeal, one on soybean meal and one on rice bran, ipil ipil leafmeal was also included in experimental diets.

On the methods of determining size/weight characteristics of food organisms of fish. (Determination of the length of Copepoda in larval stages by egg-laying females of the free living freshwater Copepoda). [Translation from: Voprosy Ikhtiologii 14, 182-194, 1960. ]

As is known, copepods play an important role in the nutrition of fish. Therefore with a view to facilitating research on the study of the quantitative side of feeding, there have recently appeared a considerable number of papers devoted to the development of methods for determining the wet. weight of these crustaceans. For the further facilitating of research in the nutrition of fish it would be of great interest to clarify the problem, is there not some kind of rule in the growth of the crustaceans during metamorphosis, and if there is such a rule is it not possible, to determine the length of the larvae at each stage, not by measuring them, but by using the formulae derived on the basis of these rules. This article examines the growth curves of different species of freshwater Copepoda, obtained on the basis of experimental observations in cultures or by way of measurement of mass material at all stages of development in samples from water-bodies. The authors study in particular the ratio of the mean diameter of the eggs to the mean length of the egg-bearing females.

Contributions to the knowledge of larval development in Cyclops leuckarti Claus [Translation from: Natura, Milano 19, 89-96, 1928]

Taxonomic observations on the larval forms of Cyclops leuckarti are being discussed and compared with Cyclops oithonoides var. hyalina. Observations include Nauplius and Metanauplius stages. The author concludes that specific differences are recognisable even in the nauplius stages.

Feeding of larval Cricotopus silvestris F. in relation to characters of structure of oral apparatus [Translation from: C.R.Acad.Sci.USSR.100, 1191-1193, 1955]

Laboratory research was done in order to study the feeding of larval Cricotopus silvestris F. in relation to characters of structure of oral apparatus. Results of the experiments are summarised and the oral apparatus morhologically described.

Diet and condition of American Alligators (Alligator mississippiensis)in three central Florida lakes

Understanding the diet of crocodilians is important because diet affects condition, behavior, growth, and reproduction. By examining the diet of crocodilians, valuable knowledge is gained about predator-prey interactions and prey utilization among habitats. In this study, I examined the diet and condition of adult American alligators (Alligator mississippiensis) in three central Florida lakes, Griffin, Apopka, and Woodruff. Two hundred adult alligators were captured and lavaged from March through October 2001, from April through October 2002, and from April through August 2003. Alligators ate a variety of vertebrate and invertebrate prey, but vertebrates were more abundant and fish dominated alligator diets in the lakes. Species composition of fish varied among the lakes. The majority of the diet of alligators from Lakes Apopka and Woodruff was fish, 90% and 84% respectively. Lake Apopka alligators consumed a significantly (P = 0.006) higher proportion of fish in their diet. Fish were 54% of the diet of Lake Griffin alligators and the infrequent occurrence of reptiles, mammals, birds, and amphibians often resulted in a large biomass. Differences in alligator diets among lakes may be due to differences in sample size (higher numbers of samples from Lake Griffin), prey availability, habitat, prey vulnerability, or prey size. Alligator condition (Fulton’s Condition Factor, K) was significantly (P < 0.001) different among the lakes. Alligators from Lake Apopka had the highest condition, followed by those from Lake Griffin, and alligators from Lake Woodruff had the lowest condition. Composition of fish along with diversity and equitability of fish in alligator diets may have contributed to differences in condition among lakes. Condition was probably also due to factors other than diet such as alligator hunting behavior, alligator density, or year-round optimal temperature that prolongs feeding. The observed diet and condition differences probably reflect both habitat differences and prey availability in these three lakes.

Alligator Diet in Relation to Alligator Mortality on Lake Griffin, FL

Alligator mississippiensis (American Alligators) demonstrated low hatchrate success and increased adult mortality on Lake Griffin, FL, between 1998 and 2003. Dying Lake Griffin alligators with symptoms of poor motor coordination were reported to show specific neurological impairment and brain lesions. Similar lesions were documented in salmonines that consumed clupeids with high thiaminase levels. Therefore, we investigated the diet of Lake Griffin alligators and compared it with alligator diets from two lakes that exhibited relatively low levels of unexplained alligator mortality to see if consumption of Dorosoma cepedianum (gizzard shad) could be correlated with patterns of mortality. Shad in both lakes Griffin and Apopka had high levels of thiaminase and Lake Apopka alligators were consuming greater amounts of shad relative to Lake Griffin without showing mortality rates similar to Lake Griffin alligators. Therefore, a relationship between shad consumption alone and alligator mortality is not supported.

The effect of sublethal concentration of DimilinR (TH6040) on the larval development of the mud-crab Rhithropanopeus harrisii (Gould)

Sublethal DimilinR (insecticide) concentration significantly decreased the percentage survival of larval R. harrisii . This decrease was marked at low salinities, when it may have become toxic. This was true for both 25 and 30 C. Duration of larval development did not seem to be affected by sublethal DimilinR concentrations even in extremely low or high salinities. High temperature, however, shortened the time of development. No anatomical abnormality was observed. These findings are only tentative as more replicates of the experiments are needed before definite conclusions can be reached. It will be desirable to work with more salinity-temperature combinations to get a complete picture of sublethal effects under different environmental conditions.

Desarrollo larval de dos especies de Crustáceos Decápodos en el laboratorio, Pachycheles haigae Rodrigues Da Costa (Porcellanidae) y Chasmagnathus granulata Dana (Grapsidae)

The present paper is concerned with studies on the larval development of two species of crustacean Decapoda: Pachyceles haigae Rodrigues Da Costa, 1960 family Porcellanidae and Chasmagnathus granulata Dana, 1851, family Grapsidae. One preazoea, two zoeae with a total of five sub-stages, a and b, and the second zoea had sub-stages a, b and c. The greatest changes are observed in the transition from the first to the second zoea and from this to the megalopa. During the sub-stages, there occured minor changes, and a net moulting of the cuticle is not observed. The differences in these sub-stages are marked by changes in the number and shape of the appendages.

Effects of the 1997-1998 El Niño on population size and diet of the Galápagos sea lion (Zalophus wollebaeki)

The multi-annual climatic event, El Niño Southern Oscillation (ENSO) is an important factor in the population dynamics of coastal marine species in the Galápagos. The Galápagos sea lion, Zalophus wollebaeki, suffered an apparent population decline of about 50%, considering both mortality and movements away from study sites during the 1997-98 El Niño. This change was in part due to changes in the availability of sardines of the Family Clupeidae, its main prey. These declines resulted partly from elevated mortality (35%) in sea lion colonies, particularly among pups, juveniles (< 1 year old), and dominant males and as a result of movements of adults elsewhere (15%), presumably where there were alternative prey and better environmental conditions.

Ichthyoplankton community structure and comparative trophodynamics in an estuarine transition zone

Surveys were conducted to evaluate and compare assemblage structure and trophodynamics of ichthyoplankton, and their variability, in an estuarine transition zone. Environmental gradients in the saltfront region of the Patuxent River subestuary, Chesapeake Bay, were hypothesized to define spatiotemporal distributions and assemblages of ichthyoplankton. Larval fishes, zooplankton, and hydrographic data were collected during spring through early summer 2000 and 2001. Larvae of 28 fish species were collected and species richness was similar each year. Total larval abundance was highest in the oligohaline region down-estuary of the salt front in 2000, but highest at the salt front in 2001. Larvae of anadromous fishes were most abundant at or up-estuary of the salt front in both years. Two ichthyoplankton assemblages were distinguished: 1) riverine—characterized predominantly by anadromous species (Moronidae and Alosinae); and 2) estuarine—characterized predominantly by naked goby (Gobiosoma bosc) (Gobiidae). Temperature, dissolved oxygen, salinity-associated variables (e.g., salt-front location), and concentrations of larval prey, specifically the calanoid copepod Eurytemora affinis and the cladoceran Bosmina longirostris, were important indicators of larval fish abundance. In the tidal freshwater region up-estuary of the salt front, there was substantial diet overlap between congeneric striped bass (Morone saxatilis) and white perch (M. americana) larvae, and also larvae of alewife (Alosa pseudoharengus) (overlap= 0.71–0.93). Larval abundance, taxonomic diversity, and dietary overlap were highest within and up-estuary of the salt front, which serves to both structure the ichthyoplankton community and control trophic relationships in the estuarine transition zone.

Larval abundance of summer flounder (Paralichthys dentatus) as a measure of recruitment and stock status

Summer flounder (Paralichthys dentatus) is one of the most economically and ecologically important estuarine-dependent species in the northeastern United States. The status of the population is currently a topic of controversy. Our goal was to assess the potential of using larval abundance at ingress as another fishery independent measure of spawning stock biomass or recruitment. Weekly long-term ichthyoplankton time series were analyzed from Little Egg Inlet, New Jersey (1989–2006) and Beaufort Inlet, North Carolina (1986–2004). Mean size-at-ingress and stage were similar between sites, whereas timing of ingress and abundance at ingress were not similar. Ingress primarily occurred during the fall at Little Egg Inlet and the winter at Beaufort Inlet. These findings agree with those from earlier studies in which at least two stocks (one north and one south of Cape Hatteras) were identified with different spawning periods. Larval abundance at Little Egg Inlet has increased since the late 1990s and most individuals now enter the estuary earlier during the season of ingress. Abundance at Little Egg Inlet was correlated with an increase in spawning stock biomass, presumably because spawning by larger, more abundant fish during the late 1990s and early 2000s provided increased larval supply, at least in some years. Larval abundance at ingress at Beaufort Inlet was not correlated with spawning stock biomass or with larval abundance at ingress at Little Egg Inlet, further supporting the hypothesis of at least two stocks. Larval abundance at Little Egg Inlet could be used as a fishery-independent index of spawning stock size north of Cape Hatteras in future stock assessments. Larval occurrence at Beaufort Inlet may provide information on the abundance of the stock south of Cape Hatteras, but additional stock assessment work is required.

Feeding ecology of juvenile Pacific salmon (Oncorhynchus spp.) in a northeast Pacific fjord: diet, availability of zooplankton, selectivity for prey, and potential competition for prey resources

We investigated the feeding ecology of juvenile salmon during the critical early life-history stage of transition from shallow to deep marine waters by sampling two stations (190 m and 60 m deep) in a northeast Pacific fjord (Dabob Bay, WA) between May 1985 and October 1987. Four species of Pacific salmon—Oncorhynchus keta (chum) , O. tshawytscha (Chinook), O. gorbuscha (pink), and O. kisutch (coho)—were examined for stomach contents. Diets of these fishes varied temporally, spatially, and between species, but were dominated by insects, euphausiids, and decapod larvae. Zooplankton assemblages and dry weights differed between stations, and less so between years. Salmon often demonstrated strongly positive or negative selection for specific prey types: copepods were far more abundant in the zooplankton than in the diet, whereas Insecta, Araneae, Cephalapoda, Teleostei, and Ctenophora were more abundant in the diet than in the plankton. Overall diet overlap was highest for Chinook and coho salmon (mean=77.9%)—species that seldom were found together. Chum and Chinook salmon were found together the most frequently, but diet overlap was lower (38.8%) and zooplankton biomass was not correlated with their gut fullness (%body weight). Thus, despite occasional occurrences of significant diet overlap between salmon species, our results indicate that interspecific competition among juvenile salmon does not occur in Dabob Bay.

Larval development of the spotfin tonguefish (Symphurus oligomerus Mahadeva and Munroe, 1990) (Pleuronectiformes: Cynoglossidae) from the Gulf of California, Mexico

Larval and early juvenile stages of Symphurus oligomerus are described from 24 specimens from the Gulf of California. Meristic features were 48 – 49 total vertebrae, 87–94 dorsal-fin rays, 73–77 anal-fin rays, 12 caudal-fin rays, and five hypural bones. Seven larvae and one juvenile were cleared and stained to obtain the pterygiophore formula (1-3-2-2-2) that confirmed the identification of S. oligomerus. The pigment pattern from preflexion to juvenile stage consists of three bands on the dorsal margin and two bands on the ventral margin formed by star-shaped melanophores on the left side of the body. The intestine in preflexion to postflexion larvae forms an abdominal projection that ends in a short conical appendix. The intestine is supported by three cartilaginous struts; larvae with these physical attributes are called exterilium larvae. Preflexion larvae have two elongated dorsal-fin rays, and in flexion to postflexion larvae the second to the fourth dorsalfin rays are elongate. We found an apparent connection between the size at metamorphosis of the species of Symphurus and the depth distribution range of adults such that the fish species that metamorphose at a larger size have a deeper distribution as adults and exterilium larvae seem to correspond to species that have deeper distributions.

Feeding ecology of Atlantic bluefin tuna (Thunnus thynnus) in North Carolina: diet, daily ration, and consumption of Atlantic menhaden (Brevoortia tyrannus)

Diet, gastric evacuation rates, daily ration, and population-level prey demand of bluefin tuna (Thunnus thynnus) were estimated in the continental shelf waters off North Carolina. Bluefin tuna stomachs were collected from commercial fishermen during the late fall and winter months of 2003–04, 2004–05, and 2005–06. Diel patterns in mean gut fullness values were used to estimate gastric evacuation rates. Daily ration determined from mean gut fullness values and gastric evacuation rates was used, along with bluefin tuna population size and residency times, to estimate population-level consumption by bluefin tuna on Atlantic menhaden (Brevoortia tyrannus). Bluefin tuna diet (n= 448) was dominated by Atlantic menhaden; other teleosts, portunid crabs, and squid were of mostly minor importance. The time required to empty the stomach after peak gut fullness was estimated to be ~20 hours. Daily ration estimates were approximately 2% of body weight per day. At current western Atlantic population levels, bluefin tuna predation on Atlantic menhaden is minimal compared to predation by other known predators and the numbers taken in commercial harvest. Bluefin tuna appear to occupy coastal waters in North Carolina during winter to prey upon Atlantic menhaden. Thus, changes in the Atlantic menhaden stock status or distribution would alter the winter foraging locations of bluefin

Diet composition and prey selection of the introduced grouper species peacock hind (Cephalopholis argus) in Hawaii

The introduced grouper species peacock hind (Cephalopholis argus), was the dominant large-body piscivore on the Main Hawaiian Island (MHI) reefs assessed by underwater visual surveys in this study. However, published data on C. argus feeding ecology are scarce, and the role of this species in Hawaiian reef ecosystems is presently not well understood. Here we provide the first comprehensive assessment of the diet composition, prey electivity (dietary importance of prey taxa compared to their availability on reefs), and size selectivity (prey sizes in the diet compared to sizes on reefs) of this important predator in the MHI. Diet consisted 97.7% of fishes and was characterized by a wide taxonomic breadth. Surprisingly, feeding was not opportunistic, as indicated by a strongly divergent electivity for different prey fishes. In addition, whereas some families of large-body species were represented in the diet exclusively by recruit-size individuals (e.g., Aulostomidae), several families of smaller-body species were also represented by juveniles or adults (e.g., Chaetodontidae). Both the strength and mechanisms of the effects of C. argus predation are therefore likely to differ among prey families. This study provides the basis for a quantitative estimate of prey consumption by C. argus, which would further increase understanding of impacts of this species on native fishes in Hawaii.