The Carr Lake Project: Potential Biophysical Benefits of Conversion to a Multiple-Use Park

The Carr Lake Project aims to convert Carr Lake’s 450 acres of agriculture fields into a regional multi-use park that will benefit flood protection, water quality, and wildlife habitat, while also providing additional recreational areas for the local community. The Project is represented by an informal consortium of interested parties including the Watershed Institute of California State University Monterey Bay, The City of Salinas, 1000 Friends of Carr Lake, and the Big Sur Land Trust. (Document contains 54 pages)

The potential impact of Ocean Thermal Energy Conversion (OTEC) on fisheries

The commercial development of ocean thermal energy conversion (OTEC) operations will involve some environmental perturbations for which there is no precedent experience. The pumping of very large volumes of warm surface water and cold deep water and its subsequent discharge will result in the impingement, entrainment, and redistribution of biota. Additional stresses to biota will be caused by biocide usage and temperature depressions. However, the artificial upwelling of nutrients associated with the pumping of cold deep water, and the artificial reef created by an OTEC plant may have positive effects on the local environment. Although more detailed information is needed to assess the net effect of an OTEC operation on fisheries, certain assumptions and calculations are made supporting the conclusion that the potential risk to fisheries is not significant enough to deter the early development of IDEe. It will be necessary to monitor a commercial-scale plant in order to remove many of the remaining uncertainties. (PDF file contains 39 pages.)

Growth response, feed conversion rate and cost benefits of hybrid catfish fed maggot meal based diets in outdoor tanks

The growth response, feed conversion ratio and cost benefits of hybrid catfish, Heterobranchus longifilis x Clarias gariepinus fed five maggot meal based diets were evaluated for 56 days in outdoor concrete tanks. Twenty-five fingerlings of the hybrid fish were stocked in ten outdoor concrete tanks of dimension 1.2mx0.13mx0.18m and code MM sub(1)-MM sub(5) in relation to their diet name. Five isonitrogenous and isocaloric maggot meal based diets namely MM sub(1)-0% maggot meal, MM sub(2)-25% maggot meal, MM sub(3)-50% maggot meal, MM sub(4-)75% maggot meal and MM sub(5-) 100% maggot meal were used for the experiment. The higher the proportion of maggot in the meal, the higher the ether extract and crude fiber. No significance difference P>0.05 exists between ash content of the experimental diets. Diet MM sub(2) had the best growth performance and highest MGR with a significant difference P<0.05 with other diets fed fish. No significance differences P>0.05 exists between the growth parameters for diets MM sub(1), MM sub(3), and MM sub(4). A positive correlation (r=1.0) exists (P<0.05, 0.25) between the growth parameters for the different experimental diets. Highest correlation r super(2)=0.9981 exists P<0.05 between MGR within the treatments. However, there no significant (P>0.05) difference in expenditure but there is between the profit indices and incidence of cost between the trials. MM sub(2) has the best yield cost and net profit. Without any reservation, inclusion of maggot based meal diet is recommended as feed of hybrid catfish to 75% inclusion for growth and profit incidence

Feed conversion, protein efficiency, digestibility and growth performance of Oreochromis niloticus fed Delonix regia seed meal

Oreochromis niloticus fingerlings (mean weight 5.27~c0.29g) were fed raw and boiled Delonix regia seed meals following standard procedures. The weight gain, specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), net protein utilization (NPU) were determined as growth indices. Diet formulated with seed boiled for 80 minutes showed significantly (P<0.05) high values for the growth indices. Carcass nutrients composition were significantly (P<0.05) higher than in the control (raw) diet. Delonix regia seed meal when boiled has high potential of being utilized efficiently by O.niloticus. The implications of the respective index in fish metabolism are discussed

Prosomal-width-to-weight relationships in American horseshoe crabs (Limulus polyphemus): examining conversion factors used to estimate landings

Horseshoe crabs (Limulus polyphemus) are valued by many stakeholders, including the commercial fishing industry, biomedical companies, and environmental interest groups. We designed a study to test the accuracy of the conversion factors that were used by NOAA Fisheries and state agencies to estimate horseshoe crab landings before mandatory reporting that began in 1998. Our results indicate that the NOAA Fisheries conversion factor consistently overestimates the weight of male horseshoe crabs, particularly those from New England populations. Because of the inaccuracy of this and other conversion factors, states are now mandated to report the number (not biomass) and sex of landed horseshoe crabs. However, accurate estimates of biomass are still necessary for use in prediction models that are being developed to better manage the horseshoe crab fishery. We recommend that managers use the conversion factors presented in this study to convert current landing data from numbers to biomass of harvested horseshoe crabs for future assessments.

Food conversion efficiency and the von Bertalanffy growth function 1: a modification of Pauly's model

A simple modification of Pauly's model for relating food conversion efficiency (K sub(1)) and body weight is proposed. The key parameter is an index to how efficiently food can be absorbed; the other parameter is related to the surface-limiting growth, an important component of von Bertalanff's and Pauly's theories of fish growth.

Food conversion efficiency and the von Bertalanffy growth function. Part II and conclusion: Extension of the new model to the generalized von Bertalanffy growth function

The simple model relating food conversion efficiency (K sub(1)) to body weight derived from the theoretical concepts behind von Bertalanffy's growth model, is extended here in the context of Pauly's generalization of that model. The exponent, which was fixed to 1/3 in the simple model, is in the extended model equivalent to 1-d, with d being the weight exponent of the anabolism term in Pauly's growth model. This makes the model applicable to fish for which the assumptions of the original (special) version of von Bertalanffy's growth model are violated.

Comparison of growth and conversion efficiency of the freshwater prawn Macrobrachium malcolmsonii (H. Milne Edwards) juveniles fed with formulated and commercial feeds

A nutritional study was carried out to know the feasibility of formulated and commercial feeds on the growth of juveniles of the freshwater prawn Macrobrachium malcolmsonii. Best relative growth rate was observed for feed 1 followed by feeds 2 and 3. Animals fed with feed 1 showed higher production than the other feeds. Higher assimilation efficiency was noticed in the animals provided with feeds 5 and 4. Higher gross and net growth efficiencies were observed in the animals offered feed 1. Among the commercial feeds, feed 3 may considered to be suitable alternative to feed 1.

The effect of feeding rate on the growth, food conversion and protein efficiency of silver dollar, Metynnis schreitmulleri (AHL), fry

A 30-day experiment was conducted to determine the effects of varying feeding rates on the growth of fry of silver dollar, Metynnis schreitmulleri (Ahl). Silver dollar fry with an average initial body weight of 1.100 ± 0.029 g were collected from a local fish breeder and fed a diet (35% protein and 6% fat) at the rate of 3, 6 and 9% of body weight per day in two equal meals. Per cent weight gain increased from 54.54 to 118.18 with increased feeding rates, which were significantly different (p<0.05) from each other. The highest specific growth rate was obtained in the fry fed at 9% body weight per day. In another study for 30 days, the effects of feeding frequency on growth, feed conversion and protein efficiency of silver dollar fry were evaluated. Groups of silver dollar fry with an initial individual weight of 0.700 ± 0.019 g were offered feed continuously for 24 hours during the day or night at different time intervals with varying meal sizes. The night time feeding with two meals gave the lowest weight and length gains (0.985 g and 0.30 cm). The growth rates of fish fed during day with three equal-sized meals are significantly (p<0.05) higher (4.66%) than the other treatments.

Utilization of prawn waste: isolation of chitin and its conversion to chitosan

process is described for the preparation of chitosan from prawn waste. The process involves extraction of protein using 0.5% sodium hydroxide solution, bleaching the protein free mass with bleach liquor containing 0.3-0.5% available chlorine followed by demineralisation with 1.25 N hydrochloric acid in the cold and deacetylation using 1:1 (w/w) sodium hydroxide solution at 100°C for 2 hours.

Impact of mangrove conversion

The article presents the impact of mangrove conversion on fisheries and on coastal areas. The mangrove areas which serve as nursery grounds for important species of fish and crustaceans are also rich feeding ground for many species from various trophic levels. Thus, the destruction of mangroves could affect the availability of fry and broodstock and, consequently, aquaculture production and fisheries. While in coastal areas, the destruction of mangroves increased the risk of coastal erosion from storm surges and winds, accelerates the erosion of riverbanks, exposes acid sulfate soils, leading to poor production and mass mortality of stocks, and affects the freshwater supply through salt intrusion upstream among others.