Energy analysis of the ring seine operations, off Cochin, Kerala

Ring seines are lightly constructed purse seines adapted for operation in the traditional sector. Fish production and energy requirement in the ring seine operations, off Cochin, Kerala, India are discussed in this paper, based on data collected during 1997- 1998. The results reflect the Gross Energy Requirement (GER) situation that existed during 1997-1998. Mean catch per ring seiner per year worked out to be 211.9 t of which sardines (Sardinella spp.) constituted 44.3%, followed by Indian mackerel (Rastrelliger kanagurta) 29.7%, carangids 11.4%, penaeid prawns 2.2%, pomfrets 1.1% and miscellaneous fish 11.3%. Total energy inputs into the ring seine operations were estimated to be 1300.8 GJ. Output by way of fish production was determined to be 931.85 GJ. GER is the sum of all non-renewable energy resources consumed in making available a product or service and is a measure of intensity of non-renewable resource use. GER per tonne of fish landed by ring seiners was estimated to be 6.14. Among the operational inputs, kerosene constituted 73.4% of the GER, followed by petrol (12.7%), diesel (6.7%) and lubricating oil (2.4%). Fishing gear contributed 3.8%, engine 0.8% and fishing craft 0.3% of the GER. Energy ratio for ring seining was 0.72 and energy intensity 1.40.

Biology of Balanus amphitrite communis (Darwin) in the Cochin harbour waters

Seasonal viariations in the incidence on fresh surfaces, breeding season, rate of growth and mortality of Balanus amphitrite communis was studied for a period of twelve months in the Cochin harbour waters, situated 76̊ 14'E and 90̊ 57'N, and subjected to annual seasonal changes in salinity.

The four seam trawl nets operated off Cochin: an analysis of the design aspects: the integration of the various parts of trawl

A study has been made of 22 different designs of four seam trawls operated at Cochin for shrimp trawling. Formulae for the relations between the different parts of the nets have been derived.

An experiment conducted with a floating trawl net off Cochin

The paper deals with an experiment with a floating trawl net off Cochin, using a pair of curved otter boards and a transducer mounted on the head rope of the net. 32 hauls were made with different towing speeds and warp length keeping one factor constant for varying parameters of the other factor. The working data for 32 hauls are presented and the effect in the fishing depth of the net due to the variation in one factor is mentioned. The 'fishing depth' is indicated in this paper as the distance between the head rope and the bottom. The usefulness of similar experiments with added information on the angle of leading warp at the stern for the exploitation of column fishes in Indian waters is indicated.

Oceanographic importance of the Cochin littoral

Situated as it is on the north-western section of the Indian Ocean, the Cochin littoral has played a very significant role in the history of India. Despite being an extremely interesting region from the point of view of oceanographic studies, the Indian Ocean in general has been one of the least scientifically known regions of our planet.

On the troll line investigations off Cochin during five fishing seasons. Pt. 1. Investigations during 1960-61 and 1961-62 seasons

There is apparently great scope for improvement of the design and operational aspects of the gear particularly for the effective exploitation of seasonal fisheries like that of seer, tuna, barracuda etc. In order to evolve improved, yet cheap trolling gear regular investigations were undertaken by the Craft & Gear Wing of the Central Institute of Fisheries Technology, off Cochin for five fishing seasons and the results of these studies are incorporated in this paper.

On the troll line investigations off Cochin during five fishing seasons. Pt. 2. Investigations during 1963-64 season

During this season the investigations were mainly directed towards elucidation of the selective action of trolling lures. Feather jigs, buffalo horn jigs, stainless steel jigs, Japanese whale bone jigs and plastic jigs were selected. Operations were carried out from Fisheries technology No. 5.

Seasonal fluctuation in the distribution of eggs and larvae of flat fishes (Pleuronectiformes - Pisces) in the Cochin backwater

Attempts have been made to correlate the abundance of eggs and larvae of flat fishes belonging to families Cynoglossidae and Soleidae with the hydrographical parameters of the environment, particularly the salinity. The eggs and larvae were found to occur in the Cochin backwater during the pre-monsoon period but not during the south west monsoon period. During the south west monsoon period larvae belonging to very early stages were found at the marine end (Fairway Buoy). The continued or prolonged existence of very low salinity appears to restrict the distribution of flat fish larvae. In the post-monsoon period also the eggs and larvae were not found in regions of very low salinity. Larvae of Cynoglossus puncticeps (Richardson), C. brevis Gunther, C. cynoglossus (Ham. Buch), C. lida (Bleeker) and Solea heinii Steindachner were obtained in the collection taken from the estuary. From the data it is seen that each species has specific spawning period.

On the troll line investigations off Cochin during five fishing seasons. Pt. 3. Investigations during 1965-66 and 1966-67 seasons

During these two seasons investigations were carried out with a view to exploring the possibility of this operation on commercial basis and to study the effect of certain meteorological factors on catch.

Emigration dynamics of three species of penaeid prawn from backwaters and tidal ponds of Cochin, India

Emigration of three species of penaeid prawn from backwaters and tidal ponds were studied. Considerable diel, tidal, lunar and seasonal fluctuations were observed in emigration process, which was almost nocturnal. Rate of emigration and composition of emigrants varied with time of migration. Large pulses of emigration always coincided with spring tides with major peak during new moon. Seasonal variation was observed with peak emigration of Penaeus indicus during monsoon months and that of Metapenaeus dobsoni and Metapenaeus monoceros during pre-monsoon. Rate of emigration was relatively large from shallow tidal ponds. It correlated directly with the prevailing environmental conditions and juvenile density. Instantaneous rate of emigration was also large in seasonal ponds. The basic stimulus for emigration is the urge for sexual maturation. Coupled with it ecological changes in the habitat have been causing various patterns in migration.

Salinity and survival of Martesia striata (Linn) in Cochin harbour

The effects of salinity variations on the survival of Martesia striata from Cochin harbour are presented. It is observed that at least a few of the animals survive the low saline conditions during monsoon. Laboratory experiments showed the lethal salinity as 6‰ when animals acclimatised in 34‰ were subjected to abrupt changes in salinity. But acclimatisation to 17‰ salinity showed a downward shift in the lethal salinity to 4‰. The present observations indicate that M. striata is euryhaline arid the extent of tolerance to lower salinities depends on the degree of acclimatisation.

Studies on the occurrence and growth rates of two intertidal fouling bryozoans in the Mattancherry channel of Cochin harbour, south-west coast of India

Occurrence and growth rates of two species of intertidal fouling bryozoans namely Electra bengalensis (Stoliczka) and Electra crustulanta (Pallas) are presented in this paper. The former was a typically marine form, settling on panels only during the high saline conditions of the pre-monsoon period and were absent during the low salinity conditions of the monsoon period, while the latter appeared to be a typical brackish water form settling on panels during the low saline conditions existing during the monsoon and post-monsoon periods and were totally absent during the pre-monsoon months. Regression co-efficient of the former was higher than that of the latter suggesting more pronounced growth in Electra bengalensis. Maximum growth for this species was noticed during March, April and May (pre-monsoon) while for the other species growth was more or less similar during monsoon and post-monsoon months (June-January) showing that the species was at home in oligohaline and mesohaline waters.

Observations on the fouling characteristics of four bryozoans in Cochin harbour

The occurrence of the four species of bryozoans under study showed that Electra crustulenta PALLAS and Victorella pavida KENT are brackish water forms, Electra bengalensis stoliczka and Schizoporella cochinensis Menon and Nair are typical marine forms. It is interesting to note the seasonal succession of these species in Cochin harbour correspond to the distribution of salinity in this area.

Investigations on long distance transportation of fish 1. Transportation of frozen fish from Cochin to Calcutta

Oil Sardine (Sardinella longiceps), mackerel (Rastrelliger kanagurta), cat fish (Arius sp.), threadfin bream (Nemipterus japonicus) and ribbon fish (Trichurus sp.) were frozen in glazed/unglazed blocks, packed in expanded polystyrene (EPS) insulated plywood boxes with and without additional ice and despatched in uninsulated parcel vans of trains from Cochin to Calcutta. The consignments reached the destination in excellent condition and were readily disposed off.

Report on the occurrence of one subspecies of Scylla serrata (Forskal) in Cochin backwaters

The taxonomy of the mud crab, Scylla serrata has become a topic of interest. Alcock (1899) described this species from Indian waters. It was considered that under the genus Scylla, only one species, namely, Scylla serrata was valid. But Estampador (1949) revised the genus and reported the occurrence of four sorts, Scylla serrata, S. tranquebarica, S. oceanica and a variety S. serrata, var paramarnosain in Philippine waters. He established his claim based on the morphology such as colouration, relative length of chelae and also on the cytological events during gametogenesis. Serene (1952) pointed out that two distinct categories under this genus were demonstrable on the basis of colouration. But Stephenson & Campbell (1960) concluded them as only synonyms, but pointed out the need for further investigations.