A re-description of the little known rabbit fish Siganus lineatus (Cuvier and Valenciennes) (Pisces:Siganide) with notes on siganid fishes of the Vembanad Lake

Siganus lineatus (Cuv. and Val) is reported from the coast of peninsular India for the first time and a detailed description of it is given based on morphology and meristic characters. It differs from the other allied species of the genus Siganus Forskal in having an oval body without spots and having fifteen parallel longitudinal golden yellow bands, relatively larger last dorsal spine, maxillary position far below the level of the orbit and cheek with distinct rows of scales. S. javus (Linnaeus) and S. canaliculatus (Park) were also obtained from the Vembanad Lake. Short notes on the habitat, occurrence, abundance, seasonal and geographic distribution in relation to fluctuating hydrological conditions of the Vembanad Lake are incorporated together with a key for their identification.

Notes on the induced maturation and spawning in four-month-old Penaeus monodon Fabricius by eyestalk ablation

The ablation technique consisted of making an incision across the eyeball to allow free flow of fluids while holding the prawn under water, squeezing the eyeball contents outwards, and pinching hard the eyestalk tissue. The cut area heals completely in about a week; no application of antibiotics is necessary. Spent spawners were tagged with thin brass rings (Rodriguez, 1976) around the unablated eyestalk for a separate experiment on rematuration. Two spawning yielding approximately 277,000 eggs were obtained three weeks after ablation, followed four days later by two more spawnings with 160,000 eggs; all four spawners weighed more than 100 g. With a hatching rate of 98% and 78% for the first and second batch, respectively, the spawnings produced viable nauplii. Water temperatures as low as 23 degree C due to a delayed cold spell in March depressed molting; weakened larvae had to be discharged at the mysis stage. Although ovarian development continued, no further spawnings were obtained due mainly to the onset of bacterial and fungal disease. Infection is initiated in injured portions of the exoskeleton, sometimes penetrating right through the muscles to the ovarian tissues. The non-flowthrough conditions and mussel meat feeding led to fouling of the culture water resulting in consecutive mortalities caused by disease. Female P.monodon held in maturation pens were ablated at the age of 15 months (Santiago, et al., 1976); they averaged only 16 g body weight after four months growth in ponds. In another experiment, pond-reared P.monodon females ranging from 50 to 80 g were ablated at approximately seven months (Aquacop, 1977). The present results show a minimum age of four months from postlarve that P.monodon is capable of ovarian development and spawning upon ablation. However, maturation is probably affected by size as well as age - the four-month old females weighed an average of 100 g in contrast to the smaller animals in the earlier experiments.

Notes on the external sex characters of Chanos chanos Forskal spawners

In the present study, no visible differences between the sexes of C. chanos with reference to external features such as colouration, shape of head, snout and operculum, presence of tubercles or nasal pores, length, size and shape as well as any roughness in the various fins, could be found. However, the anal region of the mature milkfish (sabalo) exhibits discernible anatomical differences in the male and female. The male has two main openings visible externally: the anterior anus and the posterior urogenital opening at the tip of the urogenital papilla. The female has three main openings instead of two: the anteriormost anus, followed by the genital pore and the urinary pore located posterior to the genital pore at the tip of the urogenital papilla. Internal examinations were also made on both sexes. In ripe sabalo, it is easier to distinguish the sexes since milk oozes out of the urogenital pore by pressing the abdomen of the ripe male fish. Gravid females are identified by their distended abdomens.

Notes on ovarian rematuration of ablated sugpo (prawn) Penaeus monodon Fabricius

To what extent spent P. monodon females can remature and spawn successive broods is an important question in terms of recycling spawners in a commercially viable operation. Corollary to this is the quantity and quality of fry from rematured females in comparison to those from first spawning. Of 347 experimental females, only 10.1% had a second spawning, and 1.4% a third spawning. To a large degree the low rate of rematuration is due to high spawner mortality - average survival period after spawning was only 6 days in a sample of 176 spawners. It took an average of 23 days after ablation for a prawn with undeveloped ovaries to mature and spawn. An ablated female may have another spawning in as little as 5 days after the previous one. Average fecundity was 180,000 eggs per second spawning, and 140,000 eggs per third spawning. The average number of eggs from first spawning ablated females was 110-120,000. Hatching rate was lower for rematuration: 44% for second spawnings, and 35% for third spawnings, as compared to 64% for first maturation.

Notes on the pigmentation pattern in the larval developmental stages of laboratory-reared milkfish

Milkfish fry were artificially bred and reared in the laboratory and the pigmentation pattern of the different developmental stages of the larvae are described in detail, with illustrations.

Notes on the construction of 12 cu m ferrocement maturation tank for prawn broodstock

The study aimed to develop an economical, rational and easy method of constructing ferrocement tank suitable for P. monodon maturation.

Examining the possibilty of multiplication and breeding of (Schizothorav [sic] zarudnyi) in order to restoration of regional aquatics reservations of Hamoon Lake and taking its advantag [sic] for aquaculture

Schizothorax zarudnvi, is an endemic fish of east country waters. (Triple lagoons of Hamoon and relevant water resources) that in the world it is reported in this resource specially. This fish named Hamoon mahi is one of the most economically valuable species in this region. Because of the recent years droughts, Hamoon logoon has been drive since 2000. Also, semi-wells (a semi natural resource) were affected drastically by recent drought years and their volume reduced to nearly one third of their real volume and resulted in changing at growth and reproduction physiology process in Schizothorax zanidnyi, brood stocks. Beginning of this project was done from October 2003. It's field studies begun (brood catching) since November 2001 by two methods including entangling gairs and at semi wells of Sistan that (Beach seine) had maximum rate of preparing qualified brood stocks. Broods transferred to Cyprinidea reproduction work shop of Zahak and after taking primary measures they stored in to the edaphic pools. Increasing the success safety factor (coefficient) for artificial reproduction of Sthizothorax zarudnyi , identifying the appropriate tune for Hormonal acceptance (physiological preparation of broods) is needed , so this important work was done regularly by histological studies and GSI measurements since November. Highest GSI rates of females (%80.51) and highest IV stage abundance of sexual maturity (%l 00) were observed an march. On the base of this date, Hormone therapy was done on broods on march. The used hormones are as follows Hypophysis. extraction, GnRHa and Anti Dopamin at the dozes of 3-6 ml, 20-30kg and 10-15 ml per kg body weight respectively and 2-3 times from 11-12-80 they were injected. Injected broods kept in to two circumstances, flow-through (rounded pool) and stagnant systems. In stagnant system 14 and 19 individuals of female and male (Schizothorax zauiulnri) broods, respectively injected in 11th, 15111, 19th, and 24th of march 1380. Non of the injected broods in 11 and 15 and 19th march (in stagnant Condition) answered to Hormone therapy. After final injection broods had general less activity and a few of them died. Mean temperature of brood pond waters (daily) which were injected. Fluctuated between 10-25-13. 63°c but injected broods on 24th march had different characteristics. They had pale color and had few fecundity. In this stage of injection they hadn't any successful vulation. After injection, Mean daily water temperature was 15, 88-17, 54°c. In Flowing system, 13-16 individual of males and females respectively were injected on 15th, 19th, 22th and 23th march. None of injected producers on 15th and 19th march with mean daily water temperature of 10, 25-12°c were prepared for spawning but injected producers on 22nd an 23th march with mean daily water temperature of 13.5-1 rc responded about 75-100 percent. (Schizothorax zarudnyi) brood stocks were prepared for spawning after 353-428 hours/day from final injection. Diameter of obtained eggs (before fertilization) was between 1.9-2.3 min and of fertilized eggs was 3.8mm. Fertilized eggs of (Schizothorax zarudnyi) were hatched after 6-7 days with mean water temperature of 17.08°c. Mean length of on one day larvae was 9.47 mm. Larvae was 9.47 mm. Larvae adsorbed the whole yolk sac after , 5-6 days at 17- 1°c and were prepared for releasing in to edaphic pools. Because of the lack of necessary and complementary facilities in the region , they had to release them in to veniros and growing them for 8 days. At the end of 18th day , 35000 larvae (at first) released into an edaphic pond with a volume of 150m2. After growing them for one moth , mean length and weight of new hatched larvae was 29.41 mm and 1.12►r , respectively. With respect to results of this investigation , artificial reproduction of (Schizothorax zarudnyi) Can be possible at 14-17°C and flowing water with Hormonal treatment. It -s breeding has increased development than other cultural specious in the region. Due to high economical value of this specious in Sistan and ti-s specialization east waters of Iran and having high resistance and proper growth There is a need of it's development and reproduction and culture in fish culture fanns (edaphic ponds• two-purpose pools) at the region and country.

Notes on the larval rearing scheme at SEAFDEC/AQD

For tiger shrimp, milkfish, and sea bass, larval rearing starts with the hatching of artificially spawned eggs. The eggs are stocked in larval rearing tanks, hatched, and metamorphosed larvae are fed and reared with good water management. Fry are harvested after about 30 days.

Notes on growth and feeding of Crocodilus niloticus

The Uganda Fisheries Department had for some time, kept Nile crocodiles in captivity, and had thus collected a considerable amount of data on growth and feeding rates. It had also devised marking and handling techniques, and a system of pens and enclosures to deal with crocodiles up to 3 m. long. The following account describes these techniques and results, which followed a study of a proposed commercial crocodile farm.

Notes on the decline of the dug-out canoe on Lake Albert

Cadwalladr and Stoneman drew attention to the fact that dug-out canoe construction had ceased around the shores of Lake Albert by 1963. Up to this year, however, dug-out canoes were probably still landing the largest proportion of the commercial fisheries catch on the lake, and its associated waterways. It is only since this time that the catch from dug-outs has declined. and currently the commercial fisheries of the lake are based predominantly on motorised planked canoes.

Preliminary results from a bottom trawl survey of Lake Rudolf with additional notes on trials with a midwater frame trawl

This paper includes a short report on preliminary midwater hauls with a frame trawl. The object is (a) to study the relationship between the vertical distribution of pelagic fish and the scattering layer, and (b) to find out if certain species, which at times occur abundantly in the bottom-trawl on the shallow-water frontiers of the scattering layer, might extend into offshore waters to constitute an important pelagic resource.