Netting in Black Moss Tarn 1954

Five fishermen pulling net in Black Moss Tarn. This photo is part of a photo album that includes pictures from 1935 to 1954.

Studies on Raschel knotless netting

Production of knotless webbings is of recent origin in India. An attempt has been made to evaluate the quality of the product consequent to its introduction in the fishing industry. A method has been presented to fix up yarn specification for Raschel knotless nettings equivalent to a given knotted netting.

Observation on the lunar and tidal influence on gill netting in the Bay of Bengal

The effect of lunar and tidal influence on the landing of pelagic fish with drift gill nets has been studied for the first time from Bay of Bengal along the Orissa coast. The catchability of the gear was highest during the first quarter and lowest in the fourth quarter of the moon. The variation in catch rates during the four different quarters was not statistically significant. Contrary to the earlier belief, landing with gill net was not poor during the moonlit nights. The extensive use of bluish grey nylon twine matching with seawater in place of indigenous hemp or cotton twine, has largely eliminated the visibility of gear during the brighter phase of the moon. The rate of exploitation was found to be significantly higher during the nights of neap tide, compared to those of spring tide. A plausible explanation for this phenomenon has been offered.

Tensile strength properties of polyethylene netting twines under exposure to out-door and artificial UV radiation

Photodegradation of three types of polyethylene twines namely, polyethylene fibrillated tape twine, polyethylene flat tape twine and polyethylene monofilament twines were studied by exposing them to sunlight and artificial UV radiation. The percentage residual strength varied in the samples, the monofilament with the highest residual strength followed by fibrillated tape twine and flat tape twine. A plot of the difference between the breaking strengths of the fibrillated tape twine and the mono filament twines against any given period of exposure exhibited a linear relationship

Economics of gill netting and two boat midwater trawling

The paper deals with the economic aspects of operation of gill netting and two boat midwater trawling conducted off Cochin. The data collected on two boat midwater trawling and gill netting during 1979 and 1980-81 are presented. Gill netting was profitable at the range of 17.5 and 25.2% while two midwater trawling was profitable at the rate of 18.5 %.

T90-Steert: Letzte Untersuchungen vor der Übernahme ins EU-Regelwerk

After due consideration the EU Commission has decided in December 2005 to admit cod-ends made of netting turned 90 de-grees (T90) as an allowable alternative for the cod fishery of the Baltic. The construction was included as one of two admissibles versions into the newly issued EU regulation 2187/2005 on technical measures for the conservation of fishery resources of the Baltic. This contribution describes some of the investigations preceeding that decision with which some of the previous demurs could be dispelled. In the course of these experiments it was detected that the cod-end netting material plays an important role for the mesh selection of a T90 cod-end, whereas the netting twine diameter is negligible. Problems with modern twine mate-rial have to be taken in consideration for constructional changes of T90 cod-ends. A relation of 1 to 2 in the circumferences in meshes at the joining round between last row of the belly and extension/cod-end turned out to be acceptable. Both the hauling technique (sidetrawler or sterntrawler) and an extensive use in the commercial fishery proved to be of no relevance for to the selection of T90 cod-ends. Taken alone, the different hydrodynamic conditions in a cod-end are insufficient to fully explain the selection phenomena. This was demonstrates by the material-related differences in selectivity of T90 cod-ends.

Eine zusätzliche Möglichkeit für die Ostseedorsch-Fischerei: Steerte aus 90° gedrehtem Netztuch

In 2004, comparative selectivity investigations were made with the now legal BACOMA codend of 110 mm mesh opening and alternative codends made of netting turned 90° of similar mesh openings on both commercial boats and on research vessels. The results show a certain variability of the BACOMA results – depending on ship type and season (L50 varying between 36,8 and 40,6) – and a general equal efficiency of codends made of netting turned 90° of the same mesh opening. Underwater observations and reduced performance of codends of equal circumference in meshes as the joining round at the end of the tapered part of the trawl indicate the need to reduce the relation of the cir-cumferences of codend and extension to 1 to 0.7 to achieve optimum fit and selectivity.

Netzmaterial und Selektivität in der Ostseedorschfischerei

Since some time fishing gear scientists express their concern over an observed tendency of the commercial fishery to proceed from codend netting yarns of 3 to 4 mm to higher values or to switch to the use of double instead of single yarn. A recent large EU-financed project collected statistical evidence on the detrimental effect of such behaviour on the selectivity of the codends. In this context data on cod are very scarce. German-Polish experiments in the Baltic from 1999 to 2001 aimed at filling this gap. The investigations prove a clear evidence of a negativ ecorrelation between netting yarn diameter and selectivity factor and/or L50. In addition they demonstrate a clear negative effect on selectivity when switching from single to double yarn The effects are of an order of magnitude that counteracting effects as catch size are masked and support the decision of the IBSFC to define maximum yarn diameters both for single and double yarn netting. A measuring instrument for the enforcement of these new regulations was introduced right in time.

Ein neues Messgerät zur Kontrolle der Maschenöffnung in der Fischerei

At present both the wedge gauge and the ICES mesh gauge are used to examine the mesh opening of trawl cod-ends. A thorough investigation of both instruments by an EU project (MESH) has revealed a number of deficiencies. This has lead to the conclusions to not further recommend the use of both devices but to go for the development of a complete new measurement tool. This is presently progressing in a further EU project named OMEGA. Prototypes of the new device have been produced and a number of introductory tests have already been made. This contribution reports on further laboratory tests carried out at the Institute for Fishing technology and Fish Quality with special emphasis on netting yarn diameters below 4 mm. The results demonstrate further yarn size depending inaccuracies of the wedge gauge and support the rapid introduction of the newly developed measurement instrument.

Ostseedorschselektion - bestehende und vorgesehene neue technische Maßnahmen

Since the beginning of the nineties the situation of the Baltic cod stock is deteriorating constantly. The fishery administration (International Baltic Sea Fisheries Commission) tries to counter this by issuing new technical measures. Existing measures (raise of mesh opening from 105 to 120 mm, “Danish” and “Swedish” escape windows) and newly introduced technical measures (BACOMA codend and raise of the mesh opening in conventional codends to 130 mm) show a number of deficiencies putting their efficiency in doubt. Available well tested alternatives to the newly introduced measures without their negative side effects (codends made of netting turned by 90°, and other designs) are presently left out of regard. Models of socioeconomic effects are likewise ignored.

Selektionsuntersuchungen an Schleppnetzsteerten für den Plattfischfang in der Ostsee

The intensified trawl fishery for flounder and otherflatfishes along the German Baltic coast during summer months resulted in the problem of increased undersized bycatches and their discarding. Thereforeselectivity trials with a standard codend, a codend withenlarged meshes and a so-called multipanel codendwith partly transverse netting were investigated. Results show that improvements in selectivity are possible, and tests including UW-TV observations shouldbe continued.

Neues aus der Selektionsforschung am Ostseedorsch

In account of the decision of the IBSFC (International Baltic Sea Fisheries Commission) to admit alternative codend constructions to the presently legal of diamond meshes with 120 mm mesh opening, since seven years a vivid research activity is encouraged at the fishing technology institutions around the Baltic. Though a center of gravity in this field of research lies in the EUproject BACOMA (participants Finland Sweden, Denmark) also the corresponding national institutes of other Baltic countries (Germany, Poland, Russia) have been active with similar investigations. German experiments in 1999 dealt with the effect of the use of netting made of double instead of single yarn on the selectivity. Further research was done on modifications of codends made from netting turned 90° from its original orientation and on simplified versions of the so-called Multipanel codend which consists of three equal diamond and three square mesh panels. The experiments demonstrated on the one hand a definite deterioration of the selective properties in a codend made from double instead of single yarn. Constructional changes in codends made from netting turned 90° on the other hand brought a further improvement of the selectivity of such codends. Finally, the investigations on the Multipanel codend revealed the overwhelming influence of the square mesh panels on the selectivity success. If in a conventional diamond codend three windows are cut out starting 50 cm from the real end of the codend in such a way that the remaining parts have the same breadth as the square mesh panels to insert, the selective effect of such a codend is remarkably improved. According to further preliminary tests this seems to be nearly independent from the type of material used.

Investment prospects in inland capture fisheries -- revolving loan scheme to artisanal fishermen

Fishing inputs in the form of the netting materials, boats and outboard engines were issued to 20 fishermen on revolving loan basis at 2 centres - Shagunu. and Monai along the western bank of Kainji Lake, Nigeria. The agreement was that the recipients should sell all their catches to the Institute and surrender 20% as part payment of the loan, until they offset the loan after which the inputs would become theirs'. The scheme was monitored for 5 years during which time most recipients had completed payment. It was observed that adequate revenue could be made from the scheme provided there was effective supervision. A proposal has been made for large scale supply of fishing inputs to one hundred fishermen. The scheme is laudable as a means of improving the lot of the fishermen and implementing management proposals in water bodies through the recipients

Fishing gear survey of Kainji Lake, northern Nigeria, 1996

A survey was carried out in September 1996 alongside the annual frame survey of Kainji Lake, Nigeria. As in the previous surveys, there were 6 main fishing gear types in use on the lake, which included gill nets, drift nets, beach seines, cast nets, longlines (baited and foul hooking) acid fishing traps. A total of 813 canoes were sampled. The canoe lengths were similar to the previous gear surveys. Altogether 466 gill nets were measured. They had an average length of 149 m, and were mostly bottom set. Of the gill nets measured 68% had a mesh size below 3 inches the minimum mesh size allowable according to the Niger and Kebbi State Fisheries Edict, 1996. Of concern was the large increase in the number of 1 inch meshed nets recorded on the lake. Drift nets had a mean length of 74 m. A total of 88% of all drift nets measured had a mesh size below 2.5 inches, the minimum mesh size stipulated in the State Edict. A total number of 102 beach seines were sampled with a mean length of 110 m, the mesh size in use on the lake remained as 0.1 inches under the Edict beach seines are banned from fishing in Kainji Lake. The decline in the lengths of the beach seines (and therefore catch rates) recorded since l995 was encouraging in the light of the destructive nature of these nets. A total of 30 cast nets were sampled, they had a mean diameter of 9.8 and a mean mesh size of 1.9 inches. All the nets had a hanging ratio of 0.5. Of the cast nets measured 40% had a mesh size below the minimum size of 2 inches recommended by the State Fisheries Edicts. Of concern was the continued rise in the number of gill nets with mesh sizes less than 2 inches. There were 2 types of longlines in operation on the lake. The baited and the foul hooking longlines. They were mostly bottom set and the hook size nos. 12-14 (Kirby sea hook) were predominant. Two types of fishing traps were identified, one was covered with a mesh of thin cane, one with netting material. The fishing traps had a mean height of 0.8 m and a mean width at the vase of 0.53 m. The mean mesh size used was 0.86 inches. Citharinus was reported as the most targeted of all fish species on the lake. Synodontis membranaceous was also targeted by most gears especially the smaller meshed nets. Labeo and Tilapia were low on the list of targeted species but their incidence remains high in the catches. (PDF contains 27 pages)

Selection of efficient hanging ratios of gillnet on fish catch in Lake Kainji, as means of alleviating poverty among artisanal fishermen in Nigeria

Five experimental gillnet each measuring 50mx 3m nylon multi filament netting of 3" by210/2 mesh size were constructed using 40%, 45%, 50%, 55% and 60% hanging percentages, the report was carried out at Yunawa fishing village on the eastern bank of Lake Kainji. The nets were set over night (6 hours approximately). Between April-July 2004, the fish caught by the five nets were recorded taking into consideration the three mode of capture i.e. enmeshing entanglement and wedging Weight number and percentage mean weight and number based on species at five different hanging ratios were analyzed in general 50% hanging ratio was found to be the best followed by 40% among others. There was significant difference (P<0.05) in the mode of capture for both hanging ratios. Most of the fish were caught by entanglement i.e. about 83% of the catch was by entanglement while 505 hanging ratio was the best considered after the report. The occurrence of species of the five hanging ratios has significant difference (P<0.05) in terms of catch by weight and number