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Alves-Stanley C.D.,University of Central Florida | Worthy G.A.J.,University of Central Florida | Worthy G.A.J.,Hubbs SeaWorld Research Institute | Bonde R.K.,U.S. Geological Survey
Marine Ecology Progress Series

The endangered West Indian manatee Trichechus manatus has 2 recognized subspecies: the Florida T. m. latirostris and Antillean T. m. manatus manatee, both of which are found in freshwater, estuarine, and marine habitats. A better understanding of manatee feeding preferences and habitat use is essential to establish criteria on which conservation plans can be based. Skin from manatees in Florida, Belize, and Puerto Rico, as well as aquatic vegetation from their presumed diet, were analyzed for stable carbon and nitrogen isotope ratios. This is the first application of stable isotope analysis to Antillean manatees. Stable isotope ratios for aquatic vegetation differed by plant type (freshwater, estuarine, and marine), collection location, and in one instance, season. Carbon and nitrogen isotope ratios for manatee skin differed between collection location and in one instance, season, but did not differ between sex or age class. Signatures in the skin of manatees sampled in Belize and Puerto Rico indicated a diet composed primarily of seagrasses, whereas those of Florida manatees exhibited greater regional variation. Mixing model results indicated that manatees sampled from Crystal River and Homosassa Springs (Florida, USA) ate primarily freshwater vegetation, whereas manatees sampled from Big Bend Power Plant, Ten Thousand Islands, and Warm Mineral Springs (Florida) fed primarily on seagrasses. Possible diet-tissue discrimination values for 15N were estimated to range from 1.0 to 1.5%. Stable isotope analysis can be used to interpret manatee feeding behavior over a long period of time, specifically the use of freshwater vegetation versus seagrasses, and can aid in identifying critical habitats and improving conservation efforts. © Inter-Research 2010, www.int-res.com. Source

Musser W.B.,University of San Diego | Bowles A.E.,Hubbs SeaWorld Research Institute | Grebner D.M.,Bioacoustician | Crance J.L.,National Marine Mammal Laboratory
Journal of the Acoustical Society of America

Limited previous evidence suggests that killer whales (Orcinus orca) are capable of vocal production learning. However, vocal contextual learning has not been studied, nor the factors promoting learning. Vocalizations were collected from three killer whales with a history of exposure to bottlenose dolphins (Tursiops truncatus) and compared with data from seven killer whales held with conspecifics and nine bottlenose dolphins. The three whales' repertoires were distinguishable by a higher proportion of click trains and whistles. Time-domain features of click trains were intermediate between those of whales held with conspecifics and dolphins. These differences provided evidence for contextual learning. One killer whale spontaneously learned to produce artificial chirps taught to dolphins; acoustic features fell within the range of inter-individual differences among the dolphins. This whale also produced whistles similar to a stereotyped whistle produced by one dolphin. Thus, results provide further support for vocal production learning and show that killer whales are capable of contextual learning. That killer whales produce similar repertoires when associated with another species suggests substantial vocal plasticity and motivation for vocal conformity with social associates. © 2014 Acoustical Society of America. Source

Vizcaino-Ochoa V.,Research Center Cientifica Educacion Superior Of Ensenada | Lazo J.P.,Research Center Cientifica Educacion Superior Of Ensenada | Baron-Sevilla B.,Research Center Cientifica Educacion Superior Of Ensenada | Drawbridge M.A.,Hubbs SeaWorld Research Institute

The California halibut (Paralichthys californicus) is a good candidate for aquaculture due to its good growth, survival and high commercial value. Several farms in the Western coast of North America are currently evaluating the potential of this species under commercial conditions. However, one of the main problems in the production of juveniles for commercial purposes is the high percentage of malpigmented fish obtained after metamorphosis (up to 80%). This problem seems to be related, among other things, to nutritional deficiencies during the larval period, in particular to the quantities and proportions of highly unsaturated fatty acids (HUFAs) in the diet. As a first approach to reduce malpigmentation, improve growth and determine the requirement for DHA in California halibut late larvae, we evaluated the effect of four levels of dietary DHA (0, 1, 2, and 4% of total fatty acids in the diet) on growth, survival, weaning success and pigmentation. DHA was administered to the larvae through enriched Artemia metanauplii. Larvae standard length and wet weight were taken during the initial stage of Artemia metanauplii supplementation (18 days post hatch, dph); at the beginning of the weaning period (50 dph); and at the end of the experiment (75 dph). We quantified the amounts of total fatty acids in 18 and 50 dph larvae. No significant differences on growth, survival and pigmentation as a result of increasing dietary DHA levels were found in 50 dph recently settled juveniles. However, larvae fed the highest DHA level resulted in the highest growth and survival at the end of the experiment (75 dph). Additionally, highest weaning success was achieved with this treatment. Significantly higher numbers of normally pigmented fish (ca., 33%) were obtained with the highest DHA level at 75 dph compared to the low DHA levels (0 and 5%). However, since this treatment resulted in the highest survival, part of the population had abnormal pigmentation (ca., 30% of the population). Based on a second order polynomial regression, the recommended DHA level in the diet for pre-metamorphic larvae to attain adequate growth and survival as estimated here for recently settled California halibut at 50 dph was 1.21% DHA of total fatty acids (TFA). However, for post-metamorphosis fish (75 dph) highest pigmentation rates, growth and survival are obtained with 2.40% DHA of TFA in the diet during the Artemia feeding period. © 2010 Elsevier B.V. All rights reserved. Source

Stuart K.R.,Hubbs SeaWorld Research Institute | Drawbridge M.A.,Hubbs SeaWorld Research Institute
Aquaculture Research

A captive population of California yellowtail (Seriola lalandi) was used to document spawning patterns, including measures of egg production, population fecundity and egg and larval quality from 2007 to 2010. Spawned eggs were also used to document larval development and to develop rearing techniques for aquaculture in the region. Broodstock growth and condition factor were best when feeding rations were maintained at 10-15% body weight week-1 during the warm summer months. A winter ration based on satiation feeding was typically 4% body weight week-1. During the 4-year study period, the only broodstock health issue was an infestation by the parasitic gill fluke Zeuxapta seriolae, which was readily treated. Spawning occurred naturally in the 140 m3 tank when the ambient water temperature reached 16°C and ended when the temperature exceeded 22°C. Egg production reached a maximum in 2010 when 43 spawn events were recorded from a pool of nine females yielding 36.8 million eggs in total. The average female size at this time was 20 kg, which equated to a total annual population fecundity of approximately 226 000 eggs kg-1 female year-1. Larval rearing trials yielded survival rates as high as 5.8% from egg to 50 days post-hatch (dph). Successful larval culture methods included the addition of algae paste for green water culture, rotifers (20 rotifers mL-1) at 2 dph and Artemia (5 Artemia mL-1) at 6 dph. Larvae were transferred from the incubation tank at 10 dph to a shallower tank with 33% greater surface area to accommodate the larvae's strong orientation to surface waters. This research represents the first documentation of successful spawning and larval rearing for S. lalandi in the eastern Pacific. © 2012 Blackwell Publishing Ltd. Source

Stuart K.R.,Hubbs SeaWorld Research Institute | Drawbridge M.,Hubbs SeaWorld Research Institute

Environmental parameters, such as light intensity and turbidity, have been shown to significantly influence the growth and survival of cultured larval finfish. Here, we study three light intensities (low: 360. lx; medium: 1675. lx; and high: 14,850. lx) and two turbidity conditions (with and without green water) to determine optimum growth and survival for California yellowtail (Seriola lalandi) larvae. The study lasted from 2 thru 16. days post hatch (dph). The high light intensity, green water treatment produced the largest larvae (865 ± 165 μg dry weight; 7.01 ± 0.07. mm notochord length), had the highest survival rate (9.2 ± 3.1%), and had the highest incidence of swimbladder inflation (68.8 ± 3.1%) among all treatments in this study. The low and medium light intensity, clear water treatments produced the smallest larvae (183 ± 60 μg dry weight; 5.58 ± 0.07. mm notochord length) and the lowest survival rate (0-0.10%). These results indicate that light intensity and turbidity are significant factors that affect growth and survival of Seriola lalandi larvae up to 16. dph. © 2011 Elsevier B.V. Source

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