The dusky rockfishes (Teleostei: Socrpaeniformes) of the North Pacific Ocean: resurrection of Sebastes variabilis (Pallas, 1814) and a redescription of Sebastes ciliatus (Tilesius, 1813)

The dusky rockfish (Sebastes ciliatus) of the North Pacific Ocean has been considered a single variable species with light and dark forms distributed in deep and shallow water, respectively. These forms have been subjected to two distinct fisheries separately managed by federal and state agencies: the light deep form is captured in the offshore trawl fishery; the dark shallow form, in the nearshore jig fishery. The forms have been commonly recognized as the light dusky and dark dusky rockfishes. From morphological evidence correlated with color differences in some 400 specimens, we recognize two species corresponding with these color forms. Sebastes ciliatus (Tilesius) is the dark shallow-water species found in depths of 5−160 m in the western Aleutian Islands and eastern Bering Sea to British Columbia. The name Sebastes variabilis (Pallas) is resurrected from the synonymy of S. ciliatus to apply to the deeper water species known from depths of 12−675 m and ranging from Hokkaido, Japan, through the Aleutian Islands and eastern Bering Sea, to Oregon. Sebastes ciliatus is uniformly dark blue to black, gradually lightening on the ventrum, with a jet black peritoneum, a smaller symphyseal knob, and fewer lateral-line pores compared to S. variabilis. Sebastes variabilis is more variable in body color, ranging from light yellow to a more usual tan or greenish brown to a nearly uniform dark dorsum, but it invariably has a distinct red to white ventrum. Synonymies, diagnoses, descriptions, and geographic distributions are provided for each species.

Economic analysis of utilizing Kainji gas kiln for fish smoking in the Kainji Lake Basin of Nigeria

Marketing of smoked fish in the Kainji Lake Basin (Nigeria) has been found to be complex, traditional and inefficient. It is also said to be limited in scope due to poor handling and processing techniques, lack of storage facilities and inadequate marketing informations. The invention of Kainji gas kiln has been found suitable to overcoming poor handling and processing techniques. This paper discusses the feasibility of operating Kainji gas kiln commercially supported with adequate storage facilities and competent management hands. The financial indicators of net present value (NPV), 47,481.11, Internal rate of return (IRR) 24% and payback period of 2.3 years that are calculated confirmed that the commercial use of Kainji gas kiln is indeed profitably feasible

Assessment of post-harvest losses in Nigeria fishery: the Kainji Lake model

The paper provides a description of a methodology used for quantitative assessment of post harvest losses in the Kainji Lake Fishery (Nigeria). The sample population was made up of 314 fisherfolk, 115 processors, 125 fish buyers and 111 fish sellers. For the determination of handling losses, 24,839 fishes weighing 2,389.31 kg belonging to 43 species were examined of which 10% by number and 9% by weight deteriorated at checking and 4% by number and 3% by weight at landing. Processing losses recorded 22% by number and 16% by weight deteriorated prior to and during smoking with the traditional 'Banda' kiln. During marketing, 16% of fish sold had deteriorated and 6% by weight of fish bought also deteriorated, mainly due to insect infestation during storage. Based on the 1995 yield estimate for Kainji Lake fishery, approximately 1000 tons of fish estimated at 80 million Naira were lost during handling alone. This figure would be much higher if the level of losses during processing and marketing are included. This assessment technique is recommended for use in obtaining quantifiable data on post harvest losses from other water bodies in Nigeria

Remote Sensing and Field Assessment of Tsunami Effects on Coastal Pond Aquaculture in Northern Sumatra

An attempt was made to conduct spatial assessment of the pattern and extent of damage to coastal aquaculture ponds along the east coast of Aceh province in Sumatra, Indonesia, resulting from the tsunami event of 26 December 2004. High-resolution satellite imagery, i.e., SPOT-5 multispectral scenes covering the 700 km stretch of the coast, acquired before and after the tsunami, were digitally enhanced and visually interpreted to delineate pockets of aquaculture ponds that were discerned to be damaged and relatively intact. Field checks were conducted at 87 sites in the four eastern coastal districts. The results indicate that SPOT-5 multispectral imagery was minimally sufficient to detect areas of damaged and relatively intact aquaculture ponds, but the 10-m spatial resolution poses limitations to evaluating the extent of pond damage. Nevertheless, the 60 km swath of the imagery makes it reasonably affordable for large-area assessment to identify pockets of severe damage for targeting more detailed assessments. The image maps produced from a mosaic of the SPOT-5 scenes can also serve as base maps for spatial planning in the challenging task of reconstruction and rehabilitation of the disrupted livelihoods of the coastal communities.

Remote sensing and field assessment of tsunami effects on coastal pond aquaculture in northern Sumatra

An attempt was made to conduct spatial assessment of the pattern and extent of damage to coastal aquaculture ponds along the east coast of Aceh province in Sumatra, Indonesia, resulting from the tsunami event of 26 December 2004. High-resolution satellite imagery, i.e., SPOT-5 multispectral scenes covering the 700 km stretch of the coast, acquired before and after the tsunami, were digitally enhanced and visually interpreted to delineate pockets of aquaculture ponds that were discerned to be damaged and relatively intact. Field checks were conducted at 87 sites in the four eastern coastal districts. The results indicate that SPOT-5 multispectral imagery was minimally sufficient to detect areas of damaged and relatively intact aquaculture ponds, but the 10-m spatial resolution poses limitations to evaluating the extent of pond damage. Nevertheless, the 60 km swath of the imagery makes it reasonably affordable for large-area assessment to identify pockets of severe damage for targeting more detailed assessments. The image maps produced from a mosaic of the SPOT-5 scenes can also serve as base maps for spatial planning in the challenging task of reconstruction and rehabilitation of the disrupted livelihoods of the coastal communities.

On the response of zooplankton in an electrical field

Zooplankton showed directional movement towards the positive electrode in an electrical field till the current continued to flow. Examination of the plankton 24 hours after their exposure for one minute to different current densities showed considerable mortality, the percentage of which was more in the case of the larger size groups.

Growth performances of three microalgal species in filtered brackishwater with different inorganic media

The growth of three microalgae species, viz., Nannochloropsis oculata, Tetraselmis chui and Chaetoceros muelleri which are commonly used in aquaculture, was investigated using three different inorganic nutrient media: (i) Modified Guillard's f/2 medium (ii) Rix Mix medium and (iii) BFRI medium. Each microalgae species was cultured for 24 days in small- scale with initial inoculation density of 17xl04 cell /ml in the three media with triplicates. N. oculata cultured in modified Guillard's f/2 medium showed superior growth with a mean peak density of 221 ±4.24 x 104 cell/ ml, to Rix Mix medium (141 ± 10.54xl04 cell/ml) and BFRI medium (47±4.94 x 104 cell/ml) on the 16th day of culture at stationary phase. Considering the increase in cell density for 20 days of culture in Rix Mix medium, C. muelleriwas significantly (P<0.05) highest than in other two media. N. oculata cultured in BFRI medium resulted in the poorest growth with a mean peak increase in density of 84±9.19 x 104 cell/ml in 12 days of culture. However, with an increase in cell density, growth of T. chui (182 ± 6.26 x 104 cell/ml) was significantly (P<0.05) higher in BFRI medium than in modified Guillard's f/2 medium. The results of the present study suggest that N. oculata and C. muelleri can be grown very well in both the modified Guillard's f/2 medium and Rix Mix medium. Better growth of T. chui can be obtained while culturing either in BFRI and Rix Mix medium. These three nutrient media used in the present study may be useful for microalgae species culture for establishing green-water culture for suitable target zooplankton, and fish and crustacean larvae in marine and brackishwater hatcheries.

Species diversification in coastal aquaculture: production potentials of shrimp (Penaeus monodon) with mono and mixed sex tilapia

An experiment of 120 days of culture was conducted in brackishwater earthen ponds having an area of 0.2ha each. The hatchery produced shrimp (Penaeus monodon) post larvae were stocked in the 40m² fine meshed nylon net nursery enclosures were fed with commercial pellet feed. After two weeks of nursing, juveniles were allowed to spread in cultural pond by opening the fence. Fingerlings of three different strain of tilapia were stocked as shrimp and Strain-1 all male (monosex) (T1), shrimp and Strain-2 all male (T2), shrimp and Strain-3 mixed sex population (T3) @ 20.000/ha and 10.000/ha, respectively and shrimp only (monoculture) (T4) @ 20.000/ha. The shrimp and fish were fed with farm made feed consisting of a mixture of fishmeal 29%, MOC 15%, rice bran 30%, soybean meal 16%, wheat flour 9% and vitamin premix 0.1%. The average final weight of shrimp was 24.9±1.13g, 23.41±3.26g and 26.67±1.89g that stocked with tilapia in treatments T1, T2, and T3 respectively. The final average weight of shrimp in monoculture (T4) was 27.41±0.76g, apparently higher but insignificant in treatments. The survival of shrimp was 42.17%, 32.38%, 39.45% and 61.98% in treatments T1 T2, T3 and T4 respectively. The production of shrimp in concurrent culture was 193.67, 154.26 and 210.41kg/ha in T1, T2 and T3, respectively, while in monoculture (T4) was 339.77 kg/ha. The growth and survival of tilapia among the treatments was insignificant. The growth of monosex tilapia ranged 225.29 and 291.31g and survival 62.77 and 72.20% in T1 and T2, respectively, in mixed sex was 193.0g and 83.20% (T3). The production of tilapia monosex strains was 1676.69kg/ha (Strain-2 all male) and 1668.98 kg/ha (Strain-1 all male) while that of Strain-3 mixed sex population was 1622.92 kg/ha.