Boat wakes and their influence on erosion in the Atlantic Intracoastal Waterway, North Carolina

Boat wakes in the Atlantic Intracoastal Waterway (AIWW) of North Carolina occur in environments not normally subjected to (wind) wave events, making sections of AIWW potentially vulnerable to extreme wave events generated by boat wakes. The Snow’s Cut area that links the Cape Fear River to the AIWW is an area identified by the Wilmington District of the U.S. Army Corps of Engineers as having significant erosion issues; it was hypothesized that this erosion could be being exacerbated by boat wakes. We compared the boat wakes for six combinations of boat length and speed with the top 5% wind events. We also computed the benthic shear stress associated with boat wakes and whether sediment would move (erode) under those conditions. Finally, we compared the transit time across Snow’s Cut for each speed. We focused on two size classes of V-hulled boats (7 and 16m) representative of AIWW traffic and on three boat speeds (3, 10 and 20 knots). We found that at 10 knots when the boat was plowing and not yet on plane, boat wake height and potential erosion was greatest. Wakes and forecast erosion were slightly mitigated at higher, planing speeds. Vessel speeds greater than 7 knots were forecast to generate wakes and sediment movement zones greatly exceeding that arising from natural wind events. We posit that vessels larger than 7m in length transiting Snow’s Cut (and likely many other fetch-restricted areas of the AIWW) frequently generate wakes of heights that result in sediment movement over large extents of the AIWW nearshore area, substantially in exceedance of natural wind wave events. If the speed, particularly of large V-hulled vessels (here represented by the 16m length class), were reduced to pre-plowing levels (~ 7 knots down from 20), transit times for Snow’s Cut would be increased approximately 10 minutes but based on our simulations would likely substantially reduce the creation of erosion-generating boat wakes. It is likely that boat wakes significantly exceed wind wave background for much of the AIWW and similar analyses may be useful in identifying management options.

Impact of mechanisation of fisheries development in Karnataka

Karnataka, one of the maritime states on the west coast of India, has progressed quite well in marine fisheries due to its vast fisheries resources and diversification in mechanised fishing. Mechanisation programmes were started by the state from 1957-58 only. Starting with two small mechanised boats, the state has today a fishing fleet of 398 purseseiners, 731 gillnetters, 2 deepsea trawlers and about 1,500 shrimp trawlers contributing over 85% of the total marine fish landings. The marine fish production during 1987-88 up to the end of March 1988 was 1,29,659 tonnes valued at Rs.48.05 crores.

Present status and future scope of fisheries in the Andaman group of islands

The coastal area of approximately 2000 km and the water-bodies in between the Andaman and Nicobar islands are rich in fishery potential which range from 0.012-0.47 million tonnes. The fishery is dominated by catches of sardines, perches, carangids, mackerels, Leiognathus elasmobranchs, seerfish, mullets and tunas. About 2050 fishermen, with 1150 country craft, 113 mechanised boats and 1367 different kinds of nets and lines are engaged in active fishing in the island. Numerous bays, lagoons and creeks are available among the group of islands for mariculture activities. The mangroves of these islands provide feeding and nursery grounds for juveniles of penaeid prawns, crabs and finfishes.

Gears and craft of Karwar: an overview

An account is given of the different types of gears and craft used to catch the pelagic and demersal fish in the inshore and estuary waters of Karwar, India. The main types of craft used during the fishing season September-May are: rampani boats, yendi boats, out-rigger boats, plank-built and dug-out canoes; important gears include: rampani, yendi, shore-seines, gill nets, boat seines, drift nets and hook and lines. Mechanized fishing, introduced during the sixties and seventies, included trawling and purse-seining. The types of gears used by the traditional fishermen depend on local conditions, seasons and distance covered from the shore. The major share to the total landings of fish in Karwar coast is brought mainly by the mechanized craft.

Studies on the storage characteristics of Silver pomfret (Pampus argentus) transported to Bombay

An investigation on the quality of pomfrets transported to Bombay from Gujarat coast and its subsequent changes during storage at room temperature and low temperature were carried out and the results reported. The pomfrets transported in boats having insulated holds were in better condition than those having non insulated holds. In general, the transported fish can be effectively stored in ice for 2 days, while the fish is in acceptable condition up to 4 days.

Mechanization of fishing craft and the use of improved fishing gear

Since the year 1925, attention has been focused periodically on the stagnation in the local fishing industry, and those who have studied the subject have been unanimous about the need to introduce modern fishing craft which are capable of working more fishing gear. This report outlines the stages through which the evolution of more effective fishing operations has progressed, both in the gradually increasing use of mechanical propulsion for boats and in the adoption of more modern gear and techniques by local fishermen. No reference is made in this report to the operation of deep-sea trawlers (Sivalingam, 1956) a phase of development which has hitherto not influenced the local fishing industry to any appreciable extent.

Fishing gear research at the Central Institute of Fisheries Technology

The Craft and Gear Wing of the Central Institute of Fisheries Technology was established to develop the country's fishing boats and implements scientifically and systematically. The Wing was organized in the year 1957 as a part of the fisheries development schemes included under the Second Five Year Plan.

Comparative fishing experiments with two trawl designs used in the inshore waters off Kakinada (Andhra Pradesh)

The importance of small trawlers for the economic exploitation of the inshore demersal fisheries is well recognized and accordingly mechanized boats of sizes 30' and 32' fitted with engines of h.p. ranging from 30 to 45 came into existence particularly at Kakinada. The need to work out the most suitable trawling gear for these classes of boats becomes imperative and as an appurtenance to this, comparative fishing experiments were attempted with different trawls. In the present communication certain observations made on the relative catch efficiency of two different trawl nets used in combination with two different shaped otter boards are given.

A report of the Fisheries Catch Assessment Survey in the Ugandan waters of Lake Victoria for the February 2008 survey

Between July 2005 and February 2008, ten Catch Assessment Surveys (CASs) were conducted at 54 pre-selected fish landing sites in the Ugandan part of Lake Victoria comprising approximately 10% of all landing sites in each of the 11 districts sharing the lake. The CASs were conducted following regionally harmonised Standard Operating Procedures (SOPs). This report covers the CAS conducted in February 2008 and puts into context the trends generated by results of the previous surveys. The catch rates of Nile perch in gillnetting boats with motor/sail, reduced from 26.9 kg boat-1 day-1 in August 2007 to 22.8 kg boat-1 day-1 in February 2008. Whereas the catch rates of paddle Sesse boats remained more or less the same as in August 2007. The Nile perch catch rates of the long line fishery of the boats using motor/sail was similar, 35 and 36 kg boat-1 day-1 in August 2007 and February 2008 respectively but the catch rates of paddle Sesse boats using long lines showed some more increase from 19 to 22 kg boat (-1) day (-1). In the tilapia fishery, the catch rates of the parachute boats using gillnets showed further decrease in a row from 12.6 kg boat-1 day-1 in December 2006, 11.6 kg boat-1 day-1 in March 2007, 11.2 kg boat-1 day-1 in August 2007 and 10.0 kg boat-1 day-1 in February 2008. The overall impact of reduced catch rates in the predominant effort groups, e.g. gillnetting boats using motor/sail in the Nile perch fishery and Parachute boats using gillnets in the tilapia fishery overshadowed the increases in less dominant effort groups and resulted in the lowest monthly catch estimates recorded in the surveys conducted since 2005. Whereas there was a clear downward trend in the Nile perch catch rates of boats using gillnets, which corroborates with the information of declining stocks from the recent Acoustics surveys, the catch rates in the long line fishery remained stable and even somewhat increasing in the last four surveys. The factors that maintain high catches against reduction of fish biomass in the long line fishery and their effects on sustainability of the Nile perch fishery should be investigated further. The Mukene fishery, characterised by large fluctuations in the catch rates did not show much change in the last two surveys in August 2007 and February 2008 and the annual catch estimates showed an overall increase of 7% from 2005 to 2007. The Mukene fishery in the Ugandan waters of Lake Victoria remained a near shore fishery in which paddle Sesse boats using small seines or scoop nets were the dominant craft.

Elevating fishers of Dal Lake in Jammu and Kashmir

The deteriorating condition of one of the most magnificent lakes of India, the Dal Lake, has provoked a lot of research interest from the biological and ecological points of view. However, the impact of deterioration of the ecology on the inhabitant fisher folk around Dal Lake has not been given much importance. In this study, the three major beats of the lake, namely, Hazratbal, Nishat and Nehru Park, were surveyed, randomly taking 10% of the fishermen families. It was observed that the summer mean catch per day (5.18 ± 0.69 kg) was more than the mean winter catch per day (2.85 ± 0.40 kg). However, the total annual catch per person was only 1195.56 ± 211.63 kg. Moreover, marketing through middlemen, especially, during summer, was observed to be very low fetching in terms of mean price per kilogram fish, amounting to Rs 37.50 ± 2.54 for local fish and Rs 22.50 ± 2.88 for the carp. It was also observed that the fisher folk had borrowed a good amount of money for the repair and construction of their houses and boats. Therefore, on the whole, the fishing business around Dal Lake was observed to be under severe stress. In this context, this paper has come out with recommendations to uplift the socio-economic conditions of the fishers.

Report of Catch Assessment Survey of Lake Albert – Albert Nile conducted in July 2012

A Catch Assessment Surveys (CAS) with the overall objective of generating information on the fish production and commercial value of the fisheries of Lake Albert and Albert Nile system was implemented by the National Fisheries Resources Research Institute (NAFIRRI) in collaboration with the Department of Fisheries Resources (DFR), Local Government staff (FOs) and BMU members at selected landing sites on Lake Albert (12 landing sites) and Albert Nile (26 landing sites) in July 2012. A total 622 and 313 boat days on Lake Albert and Albert Nile respectively were sampled for a period of 9 days. Results indicate an annual landing of 151,600 and 5,900 tonnes (t) of fish with an estimated beach value of 122.5 and 14 Billion (UShs) from Lake Albert and Albert Nile respectively. Over 80% of the catch from Lake Albert comprised the small pelagic species; Neobola bredoi (Muziri) and Brycinus nurse (Ragoogi) followed by Nile perch (6%). However, due to low market value of the small fishes and the high prices attached to Nile perch for industrial processing and export market, the contribution of the latter to beach value rose to 34% of the total. The contribution of the light fishery based on small pelagic species (B. nurse and N. bredoi) are insignificant on Albert Nile. Even if the small pelagic species may be present in the river system, a light fishery based on these two is yet to be developed. Proportionally, Albert Nile still remain a multispecies fishery with over 20 fish species harvested commercially. Interestingly, the Albert Nile fishery still remains primitive with simple crafts and gears (mainly dugout canoes, traps, and gillnets). This could suggest that the more developed the system becomes the higher the level of transformation in its fisheries leading to simplification, characterized by reduction in multispecies nature and dominance of few species. Illegal gears especially undersized gillnet of mesh size less than 4 inches were the most dominant in the Lake Albert and Albert Nile fisheries. They captured large quantities of immature fish particularly when used to target Nile perch, Bagrus, Nile tilapia, and large Barbus spp. Their impact when used to target the smaller species (Ragoogi, Angara & Ngasia) is yet to be evaluated. A specific study to analyze selectivity and impacts of these nets is a recommended. However, the dominance of 1.5” mesh sizes especially on Albert Nile to target Angara, Ngassia and Barbus, is definitely destructive to their fisheries and should be checked forthwith. In addition, there is an emerging fishing method locally referred to as “Salsio or Luzira” whereby fishers stay on the lake from 3 days up to 2 weeks without returning to the landing site. They carry with them food and salt for processing the catches on the lake, and in the case of Albert Nile on make shift shelters on islands and in the game park. They normally use gillnets of 3-3½ inch mesh size and caught mainly Nile perch & Bagrus (Pethi & Munama). On return they land several tons of fish. Most of these Catches are not captured in the estimates presented in our analyses since we target daily fishing boats. The possible impacts of this fishing method should be studied and appropriate action recommended.

Assessment and possible development of the fishery resources of Pedro Bank

Pedro Bank is about 1,300 square miles in extent and lies at the mouth of the Palk Strait close to the mainland, enabling smaller boats to exploit it. Trawl surveys indicated the presence of substantial demersal varieties on the Pedro Bank, but the results of the early commercial operations indicate that a 135-foot trawler may not be operated continuously on the bank without diminishing returns. Subsequent to the commercial operations extensive surveys with smaller boats and various types of gear were carried out. Of the various types of gear tried out, results from bottom long lining and hand lining operations were promising. Trials were carried out to compare these two types of gear. Though not extensive, these trials indicated that at the initial stages of exploitation of the Bank, hand lining, which is extensively practiced in Ceylon, may be better but as exploitation progresses; with more experience, it should be possible to overcome some of the present disadvantages of bottom long lining and eventually bottom long lining should produce better results. The recently introduced mechanised craft are exploiting only the fringe of the bank and it should be possible to exploit its stocks fully with slightly bigger boats with a 35-40 mile range.

Coastal fisheries

The coastal zone of Sri Lanka is the most important area of fish production at present. This coastal zone is limited seawards to the edge of our relatively narrow continental shelf. The fishing methods employed are such that only a fraction of the shelf area is exploited. The extent to which the coastal zone is exploited depends on the craft and gear used in the fishing operations. The non-mechanized traditional crafts such as the teppams and orus generally operate within about five miles from shore. The mechanized traditional crafts and the small mechanized boats introduced around 1957 carry out fishing operations up to the continental shelf or beyond. The gear used by these fishing crafts is determined by the habits of the type of fish to be caught, the nature of the sea bed and other related conditions. For the pelagic fishes they use trolling lines or float long lines or drift nets. For the demersal fishes hand lines, bottom long lines, bottom set nets or drag nets are used. However, the net is the preferred fishing gear. The beach seines or madels, the traditional crafts such as orus, teppams and vallams and the small mechanized boats are the important contributors in the coastal fishery. Of these the madels are considered the most important since a high percentage (25-35%) of the Island's landings are produced by the operation of these nets.

Wadge Bank trawl fishery studies. Pt. 1. The effect of the 1928 to 1935 commercial trawling on the demersal stock

The demersal fish stock of Wadge Bank is one of the important fish resources for both Sri Lanka and India. Sivalingam and Medcof (1957) have given an account of its history, general features and relative productivity. According to records the total fishing effort on the bank had been fluctuating and very recently the number of boats operating on the bank has suddenly increased, and there is a possibility that still more will begin operating on the bank in the near future (Mendis, 1965). The increased fishing effort with the possibility of still further increase calls for proper management practices by those concerned, in order to obtain the maximum sustained yield from the demersal stock. For this purpose a detailed study of the past performance of the fishery is essential. With this in view all records of commercial operations up to 1960 are being analysed by the present author and are to be published in a series. This is the first paper in the series and gives a detailed analysis of the first commercial trawling operations from 1928 to 1935. Since there had been a major break of about 10 years between this and the present fishery this data is being analysed separately.

Small mesh trawling

Experimental trawling operations for bottom fish were first begun in 1920 and consisted of surveys of the continental shelf around Ceylon and the west and east coasts of India. These preliminary surveys showed that the continental shelf of Ceylon was either very poor in bottom fish or that the ground was so rough that trawling has proved to be economically not sustainable (Malpas, 1926). Although a considerable amount of trawling has been carried out using small-meshed trawls, there is no record of the details of the gear used or any account of the relative efficiency of the different designs of trawls used in the operations. Experimental operations were, therefore, carried out off 80 h.p. boats such as m.f.v. Canadian and North Star, to select the most effective gear for these boats. In more recent times experiments were also conducted to select the most effective trawling gear for the 11-Ton boats of the Ceylon Fisheries Corporation. The results are reported in this publication.