Early life history studies of Yellowfin tuna, Thunnus albacares. I. Food selection of Yellowfin tuna, Thunnus albacares, larvae reared in the laboratory. II. Age validation and growth of Yellowfin tuna, Thunnus albacares, larvae reared in the laboratory

English: Food selection of first-feeding yellowfin tuna larvae was studied in the laboratory during October 1992. The larvae were hatched from eggs obtained by natural spawning of yellowfin adults held in sea pens adjacent to Ishigaki Island, Okinawa Prefecture, Japan. The larvae were fed mixed-prey assemblages consisting of size-graded wild zooplankton and cultured rotifers. Yellowfin larvae were found to be selective feeders during the first four days of feeding. Copepod nauplii dominated the diet numerically, by frequency of occurrence and by weight. The relative importance of juvenile and adult copepods (mostly cyclopoids) in the diet increased over the 4-day period. Rotifers, although they comprised 31 to 40 percent of the available forage, comprised less than 2.1 percent of the diet numerically. Prey selection indices were calculated taking into account the relative abundances of prey, the swimming speeds of yellowfin larvae and their prey, and the microscale influence of turbulence on encounter rates. Yellowfin selected for copepod nauplii and against rotifers, and consumed juvenile and adult copepods in proportion to their abundances. Yellowfin larvae may select copepod nauplii and cyclopoid juveniles and adults based on the size and discontinuous swimming motion of these prey. Rotifers may not have been selected because they were larger or because they exhibit a smooth swimming pattern. The best initial diet for the culture of yellowfin larvae may be copepod nauplii and cyclopoid juveniles and adults, due to the size, swimming motion, and nutritional content of these prey. If rotifers alone are fed to yellowfin larvae, the rotifers should be enriched with a nutritional supplement that is high in unsaturated fatty acids. Mouth size of yellowfin larvae increases rapidly within the first few days of feeding, which minimizes limitations on feeding due to prey size. Although yellowfin larvae initiate feeding on relatively small prey, they rapidly acquire the ability to add relatively large, rare prey items to the diet. This mode of feeding may be adaptive for the development of yellowfin larvae, which have high metabolic rates and live in warm mixed-layer habitats of the tropical and subtropical Pacific. Our analysis also indicates a strong potential for the influence of microscale turbulence on the feeding success of yellowfin larvae. --- Experiments designed to validate the periodicity of otolith increments and to examine growth rates of yellowfin tuna larvae were conducted at the Japan Sea-Farming Association’s (JASFA) Yaeyama Experimental Station, Ishigaki Island, Japan, in September 1992. Larvae were reared from eggs spawned by captive yellowfin enclosed in a sea pen in the bay adjacent to Yaeyama Station. Results indicate that the first increment is deposited within 12 hours of hatching in the otoliths of yellowfin larvae, and subsequent growth increments are formed dailyollowing the first 24 hours after hatching r larvae up to 16 days of age. Somatic and otolith gwth ras were examined and compared for yolksac a first-feeding larvae reared at constant water tempatures of 26�and 29°C. Despite the more rapid develo of larvae reared at 29°C, growth rates were nnificaifferent between the two treatments. Howeve to poor survival after the first four days, it was ssible to examine growth rates beyond the onset of first feeding, when growth differences may become more apparent. Somatic and otolith growth were also examined for larvae reared at ambient bay water temperatures during the first 24 days after hatching. timates of laboratory growth rates were come to previously reported values for laboratory-reared yelllarvae of a similar age range, but were lower than growth rates reported for field-collected larvae. The discrepancy between laboratory and field growth rates may be associated with suboptimal growth conditions in the laboratory. Spanish: Durante octubre de 1992 se estudió en el laboratorio la seleccalimento por larvaún aleta amarillmera alimentación. Las larvas provinieron de huevos obtenidosel desove natural de aletas amarillas adultos mantenidos en corrales marinos adyacentes a la Isla Ishigaki, Prefectura de Okinawa (Japón). Se alimentó a las larvas con presas mixtas de zooplancton silvestre clasificado por tamaño y rotíferos cultivados. Se descubrió que las larvas de aleta amarilla se alimentan de forma selectiva durante los cuatro primeros días de alimentación. Los nauplios de copépodo predominaron en la dieta en número, por frecuencia de ocurrencia y por peso. La importancia relativa de copépodos juveniles y adultos (principalmente ciclopoides) en la dieta aumentó en el transcurso del período de 4 días. Los rotíferos, pese a que formaban del 31 al 40% del alimento disponible, respondieron de menos del 2,1% de la dieta en número. Se calcularon índices de selección de presas tomando en cuenta la abundancia relativa de las presas, la velocidad de natación de las larvas de aleta amarilla y de sus presas, y la influencia a microescala de la turbulencia sobre las tasas de encuentro. Los aletas amarillas seleccionaron a favor de nauplios de copépodo y en contra de los rotíferos, y consumieron copépodos juveniles y adultos en proporción a su abundancia. Es posible que las larvas de aleta amarilla seleccionen nauplios de copépodo y ciclopoides juveniles y adultos con base en el tamaño y movimiento de natación discontinuo de estas presas. Es posible que no se hayan seleccionado los rotíferos a raíz de su mayor tamaño o su patrón continuo de natación. Es posible que la mejor dieta inicial para el cultivo de larvas de aleta amarilla sea nauplios de copépodo y ciclopoides juveniles y adultos, debido al tamaño, movimiento de natación, y contenido nutritivo de estas presas. Si se alimenta a las larvas de aleta amarilla con rotíferos solamente, se debería enriquecerlos con un suplemento nutritivo rico en ácidos grasos no saturados. El tamaño de la boca de las larvas de aleta amarilla aumenta rápidamente en los primeros pocos días de alimentación, reduciendo la limitación de la alimentación debida al tamaño de la presa. Pese a que las larvas de aleta amarilla inician su alimentación con presas relativamente pequeñas, se hacen rápidamente capaces de añadir presas relativamente grandes y poco comunes a la dieta. Este modo de alimentación podría ser adaptivo para el desarrollo de larvas de aleta amarilla, que tienen tasa metabólicas altas y viven en hábitats cálidos en la capa de mezcla en el Pacífico tropical y subtropical. Nuestro análisis indica también que la influencia de turbulencia a microescala es potencialmente importante para el éxito de la alimentación de las larvas de aleta amarilla. --- En septiembre de 1992 se realizaron en la Estación Experimental Yaeyama de la Japan Sea- Farming Association (JASFA) en la Isla Ishigaki (Japón) experimentos diseñados para validar la periodicidad de los incrementos en los otolitos y para examinar las tasas de crecimiento de las larvas de atún aleta amarilla. Se criaron las larvas de huevos puestos por aletas amarillas cautivos en un corral marino en la bahía adyacente a la Estación Yaeyama. Los resultados indican que el primer incremento es depositado menos de 12 horas después de la eclosión en los otolitos de las larvas de aleta amarilla, y que los incrementos de crecimiento subsiguientes son formados a diario a partir de las primeras 24 horas después de la eclosión en larvas de hasta 16 días de edad. Se examinaron y compararon las tasas de crecimiento somático y de los otolitos en larvas en las etapas de saco vitelino y de primera alimentación criadas en aguas de temperatura constante entre 26°C y 29°C. A pesar del desarrollo más rápido de las larvas criadas a 29°C, las tasas de crecimiento no fueron significativamente diferentes entre los dos tratamientos. Debido a la mala supervivencia a partir de los cuatro primeros días, no fue posibación, uando las diferencias en el crecimiento podrían hacerse más aparentes. Se examinó también el crecimiento somático y de los otolitos para larvas criadas en temperaturas de agua ambiental en la bahía durante los 24 días inmediatamente después de la eclosión. Nuestras estimaciones de las tasas de crecimiento en el laboratorio fueron comparables a valores reportados previamente para larvas de aleta amarilla de edades similares criadas en el laboratorio, pero más bajas que las tasas de crecimiento reportadas para larvas capturadas en el mar. La discrepancia entre las tasas de crecimiento en el laboratorio y el mar podría estar asociada con condiciones subóptimas de crecimiento en el lab

White spot syndrome virus (WSSV) transmission risk through infected cooked shrimp products assessed by polymerase chain reaction (PCR) and bio-inoculation studies

The aim of the study was to evaluate the resistance of white spot syndrome virus (WSSV) in shrimps (Penaeus monodon) to the process of cooking. The cooking was carried out at 1000C six different durations 5, 10, 15, 20, 25 and 30 min. The presence of WSSV was tested by single step and nested polymerase chain reaction (PCR). In the single step PCR, the primers 1s5 & 1a16 and IK1 & IK2 were used. While in the nested PCR, primers IK1 &IK2 – IK3 & IK4 were used for the detection of WSSV. WSSV was detected in the single step PCR with the primers 1s5 and 1a16 and the nested PCR with the primers IK1 and IK2 – IK3 & IK4 from the cooked shrimp samples. The cooked shrimps, which gave positive results for WSSV by PCR, were further confirmed for the viability of WSSV by conducting the bio-inoculation studies. Mortality (100%) was observed within 123 h of intra-muscular post injection (P.I) into the live healthy WSSV-free shrimps (P. monodon). These results show that the WSSV survive the cooking process and even infected cooked shrimp products may pose a transmission risk for WSSV to the native shrimp farming systems.

William Francis Thompson (1888–1965) and His Pioneering Studies of the Pacific Halibut, Hippoglossus stenolepis

William Francis Thompson (1888–1965), as a temporary employee of the British Columbia Provincial Fisheries Department, was assigned in 1914 to under-take full-time studies of the Pacific halibut, Hippoglossus stenolepis. The fishery was showing signs of depletion, so Thompson undertook the inquiry into this resource, the first intensive study on the Pacific halibut. Three years later, Thompson, working alone, had provided a basic foundation of knowledge for the subsequent management of this resource. He published seven land-mark papers on this species, and this work marked the first phase of a career in fisheries science that was to last nearly 50 years.

William Francis Thompson (1888–1965) and His Pioneering Studies of the Pacific Halibut, Hippoglossus stenolepis

William Francis Thompson (1888–1965), as a temporary employee of the British Columbia Provincial Fisheries Department, was assigned in 1914 to under-take full-time studies of the Pacific halibut, Hippoglossus stenolepis. The fishery was showing signs of depletion, so Thompson undertook the inquiry into this resource, the first intensive study on the Pacific halibut. Three years later, Thompson, working alone, had provided a basic foundation of knowledge for the subsequent management of this resource. He published seven land-mark papers on this species, and this work marked the first phase of a career in fisheries science that was to last nearly 50 years.

2007 biennial report to Congress on the progress and findings of studies of striped bass populations

The 1997 reauthorization of the Atlantic Striped Bass Conservation Act (Striped Bass Act) mandated biennial reports to Congress and to the Atlantic States Marine Fisheries Commission (Commission) from the secretaries of the Department of Commerce and the Department of the Interior concerning the progress and findings of studies of Atlantic striped bass (Morone saxatilis). The Striped Bass Act specifically requests updates on studies that include, but are not limited to: annual stock assessments, investigations on the causes of fluctuations in Atlantic striped bass populations, the effects of environmental factors on the recruitment, spawning potential, mortality, and abundance of Atlantic striped bass populations, and investigations of interactions between Atlantic striped bass and other fish. This document is the fifth such report to Congress and includes data available through 2007 with emphasis on the 2005 and 2006 calendar years.

Carfentrazone-ethyl Pond Dissipation and Efficacy on Floating Plants

Carfentrazone-ethyl (CE) is a reduced risk herbicide that is currently being evaluated for the control of aquatic weeds. Greenhouse trials were conducted to determine efficacy of CE on water hyacinth ( Eichhornia crassipes (Mart.) Solms- Laub.), water lettuce ( Pistia stratiotes L.), salvinia ( Salvinia minima Baker) and landoltia (Landoltia punctata (G. Mey.) Les & D. J. Crawford ) . CE controlled water lettuce, water hyacinth and salvinia at rates less than the maximum proposed use rate of 224 g ha -1 . Water lettuce was the most susceptible to CE with an EC 90 of 26.9 and 33.0 g ha -1 in two separate trials. Water hyacinth EC 90 values were calculated to be 86.2 to 116.3 g ha -1 , and salvinia had a similar susceptibility to water hyacinth with an EC 90 of 79.1 g ha -1 . Landoltia was not adequately controlled at the rates evaluated. In addition, CE was applied to one-half of a 0.08 ha pond located in North Central, Florida to determine dissipation rates in water and hydrosoil when applied at an equivalent rate of 224 g ha -1 . The half-life of CE plus the primary metabolite, CE-chloropropionic acid, was calculated to be 83.0 h from the whole pond, and no residues were detected in water above the limit of quantification (5 μg L -1 ) 168 h after treatment. CE dissipated rapidly from the water column, did not occur in the sediment above the levels of quantification, and in greenhouse studies effectively controlled three species of aquatic weeds at relatively low rates.(PDF contains 6 pages.)

Homarid Lobster Hatcheries: Their History and Role in Research, Management, and Aquaculture

This paper provides an historical review of homarid lobster fisheries, the development and usage of lobster hatcheries, and much of the research influenced by hatchery-initiated studies on natural history, physiology, and morphological development of the lobster, Homarus spp. Few commercial lobster hatcheries exist in the world today, yet their potential usage in restocking efforts in various countries is constantly being reexamined, particularly when natural stocks are considered “overfished.” Furthermore, many individual researchers working on homarid lobsters use smallscale hatchery operations to provide the animals necessary for their work as well as animals reared and provided by various governmental agencies interested in specific projects on larvae, postlarvae, or juveniles. Such researchers can benefi t from the information in this review and can avoid many pitfalls previously documented. The development of hatcheries and the experimental studies that were generated from their activities have had a direct impact on much of the research on lobsters. The past work arising from hatchery operations—descriptions of life stages, behavior, physiology, etc.—has generally been confirmed rather than refuted and has stimulated further research important for an understanding of the life history of homarid lobsters. The connections between homarid fisheries and hatchery operations (i.e. culturing of the lobsters), whether small- or large-scale for field and laboratory research, are important to understand so that better tools for fishery management can be developed. This review tries to provide such connections. However, the rearing techniques in use in today’s hatcheries—most of which are relics from the past—are clearly not effi cient enough for large-scale commercial aquaculture of lobsters or even for current restocking efforts practiced by several countries today. If hatcheries are to be used to supplement homarid stocks, to restock areas that were overfished, or to reintroduce species into their historical ranges, there is a clear need to further develop culture techniques. This review should help in assessments of culturing techniques for Homarus spp. and provide a reference source for researchers or governmental agencies wishing to avoid repeating previous mistakes.

Ecology and growth of juvenile California spiny lobster, Panulirus interruptus (Randall)

ABSTRACT TRANSCRIBED FROM ENGLE'S PH.D. ORAL DEFENSE PAMPHLET: The natural history of juvenile California spiny lobster, Panulirus interruptus (Randall), was investigated, with primary emphasis placed on ascertaining juvenile habitats, determining juvenile growth rates and component growth processes, and evaluating ecological and behavioral phenomena associated with juvenile survival and growth. Habitat surveys of island and mainland localities throughout southern and lower California revealed that small, greenish juveniles typically inhabit crevices or temporary burrows in 0-4m deep, wave-swept rocky habitats covered by dense beds of surf grass, Phyllospadix torreyi S. Watson. Phyllospadix beds were more abundant on gradually sloping rocky mainland beaches than on steeply sloping island shores. Phyllospadix abundance was positively correlated with P. interruptus abundance; however, at Santa Catalina Island, the Phyllospadix habitat was not extensive enough to be the sole lobster nursery. In laboratory tests, puerulus larvae and early juveniles chose Phyllospadix over rubble rocks or broad-bladed kelp, but did not consistently prefer Phyllospadix over reticulate algae. Ecology, growth, and behavior of juvenile P. interruptus inhabiting a discrete Phyllospadix habitat at Bird Rock, Santa Catalina Island, were investigated from October 1974 through December 1976 by means of frequent scuba surveys. Pueruli settled from June to November. Peak recruitment occurred from July to September, when seasonal temperatures were maximal. Settled larvae were approximately one year old. Juvenile growth was determined by size-frequency, single molt increment, mark-recapture, and laboratory culture studies. Carapace length vs. wet weight relationships fit standard power curve equations. Bird Rock juveniles grew from 7 to 32mm CL in 10-11 molts and from 32 to 56mm CL in 5-6 molts during their first and second benthic years, respectively. Growth rates were similar for males and females. Juveniles regenerating more than two limbs grew less per molt than intact lobsters. Long-term growth of laboratory-reared juveniles was 20% less than that of field lobsters. Growth component multiple regression analyses demonstrated that molt increment was directly proportional to premolt size and temperature for age 1+ lobsters. Molt frequency was inversely proportional to size and directly proportional to temperature. Temperature affected age 2+ lobsters similarly, but molt increment was independent of size, and molt frequency declined at a different rate. Juvenile growth rates more than doubled during warm water months compared to cold water months, primarily because of increased molt frequency. Based on results from this study and from previous investigations, it is estimated that P. interruptus males and females become sexually mature by ages 4 and 5 years, respectively, and that legai size is reached by 7 or 8 years of age. Juvenile P. interruptus activity patterns and foraging behavior were similar to those of adults, except that juvenile home ranges were proportionally smaller, and small juveniles were apparently not attracted to distant food. Small mollusks, abundant in Phyllospadix habitats, were the major food items. Size-dependent predation by fish and octopus apparently caused the considerable juvenile mortality observed at Bird Rock. Juveniles approaching 2 years of age gathered in mixed size-class aggregations by day and foraged beyond the grass beds at night. In autumn, these juveniles migrated to deeper habitats, coincident with new puerulus settlement in the Phyllospadix beds. Based on strong inferences from the results, it is proposed that size-dependent predation is the most important factor determining the !ife history strategy of juvenile P. interruptus. Life history tactics promoting rapid growth apparently function dually in reducing the period of high vulnerability to predation and decreasing the time required to reach sexual maturity. The Phyllospadix habitat is an excellent lobster nursery because it provides shelter from predators and possesses abundant food resources for sustaining optimum juvenile growth rates in shallow, warm water.

Study of the rocky intertidal communities of central and northern California: Years III and IV

The study objectives are to describe seasonal and successional variation in rocky intertidal community structure; determine the response of rocky intertidal communities to natural and human-induced disturbances and correlate these responses with successional, seasonal, and latitudinal variation; and correlate life history information and oil toxicity data with data from this and other relevant studies. The Year III and IV report is for the third (1987) and fourth (1988) years of a five-year field experimental study investigating two biological assemblages, the Mytilus assemblage and the Endocladia/Mastocarpus papillatus assemblage, that are being studied at six sites along the California coast. Volume I includes the report, Appendix A, and Appendix B. Volume II includes Appendix C. Volume III includes Appendix D. Volume IV includes Appendix E and Appendix F. Volume V includes Appendix G, Appendix H, and Appendix I.

Population dynamics of a cladoceran zooplankter, Daphnia magna, in two poultry-cum-fish (duck-fish and chicken-fish) integrated ponds

The population dynamics of Daphnia magna was studied in two integrated fish-cum-poultry ponds (duck-fish and chicken-fish). The seasonal changes in the population of D. magna were recorded. Peak population of the zooplankter was recorded in the month of January in both ponds. The birth rate (b), growth rate (r) and death rate {d) of D. magna were studied in field as well as in the laboratory. Three temperatures and three different food concentrations were selected for laboratory study. The maximum values of (b) and (r) were recorded during December-January in field. Under laboratory conditions, highest birth and death rate occurred at lowest temperature (15 °C). Both food and temperature were found to affect the population dynamics of the species; longest life span and maximum population were recorded at lowest temperature and maximum food concentration.