Individual Boats Research Articles

Measuring lumps: Optimising sampling of the commercial landings of lumpfish (Cyclopterus lumpus) in Iceland

Lumpfish (Cyclopterus lumpus) are the target of commercial fisheries in several countries. However, the collection of biological data for stock assessment purposes is both logistically difficult and expensive. The fishery takes place far from major population centres, over a wide geographical area, and, the roe is extracted at sea and the carcass is not landed in the majority of countries where lumpfish is fished commercially. In Iceland, a new regulation was introduced in 2012 making it mandatory to land the carcass, which led to changes within the industry that made the collection of biological data feasible, and a sampling programme was fully implemented by 2014. This study examines the precision of the sampling scheme and looks for areas in which improvements could be made. The female lumpfish landed by the fishery fell into a narrow length distribution, with the majority of fish between 36 and 47 cm total length. Average length of fish caught in the south-west (Faxaflói) was greater than fish caught on the north coast, highlighting the need to sample over the geographical extent of the fishery. A sample size of 20 fish was sufficient for a reasonably precise estimate of the length frequency of the fish caught by an individual boat. Individual boats caught fish of similar size over time, thus repeated sampling of the same boat should not be considered as separate samples. Fish stored on ice lost ~1.5–2.5% of their weight per day. From 2015–2020, measurements were taken from > 18% of the boats targeting female lumpfish; increasing the sampling effort would lead to only small increases in precision. This analysis provides valuable information in which to base future sampling schemes in other lumpfish fisheries.

Maximising Sensory Perception

Tasks undertaken by those who manned US submarines during the Second World War were only in part governed by training and rate. S P MacKenzie explores how those in authority aboard individual boats also sought out those with specific sensory abilities for certain tasks, and shows how the development of an optimum corporate sensorium was once considered vital.

Length-based stock assessment of Oreochromis mossambicus and Oreochromis niloticus (Actinopterygii: Perciformes: Cichlidae) in multi-mesh gillnet fisheries in reservoirs of Sri Lanka

Background. Gillnets of mesh sizes (6.9 to 12.7 cm) are used in individual boats in Sri Lankan reservoirs targeting exotic cichlid species, Oreochromis mossambicus (Peters, 1852) and Oreochromis niloticus (Linnaeus, 1758), which dominate the fisheries. The mesh composition of gillnets varies from boat to boat and from season to season making catch samples in individual boats are under the influence of different selectivity patterns. As such, the conventional procedure of correcting length frequency samples using the overall mean selectivity pattern in the fishery is not precise in estimating growth parameters. The presently reported study aimed at assessing cichlid stocks in three tropical reservoirs accounting for gillnet selectivity of individual sampled boats. Materials and methods. Length frequency data obtained from each boat were corrected for the combined selectivity of the fleet of gillnets of different mesh sizes used in the boat during the sampling occasion. For predicting optimal fishing strategies using a yield-per-recruit approach, probabilities of capture determined from the array of fishing mortality in the length-structured virtual population analysis was incorporated. Results. Length frequency data corrected for overall gillnet selectivity in sampled boats gave reliable estimates of von Bertalanffy growth parameters. Based on these estimates, mortality parameters were determined and the overall gear selection pattern was deduced from the array of fishing mortality in the length-structured virtual population analysis. Optimal fishing strategies were determined incorporating overall probabilities of capture in the relative yield-per-recruit (Y′ × R–1) analysis. Conclusion. The overall gillnet selection pattern of a sampled boat offers a methodology for reliable estimation of growth parameters. Although both cichlid species are caught in gillnets simultaneously, Y′ × R–1 analyses predicted increase of exploitation rate for one species while its decrease for the other species perhaps due to influence of other factors such as fish behaviour and fishers’ choice of specific areas for fishing. This analysis provides a methodology of a more precise length-based stock assessment in future research.

Multi-mesh gillnet selectivity of Oreochromis mossambicus and O. niloticus (Cichlidae) in the fishery of three large perennial reservoirs in Sri Lanka

As in many tropical reservoir fisheries, the major fishing gear in the reservoirs of Sri Lanka is gillnet. Gillnets of a wide range of stretched mesh sizes (6.9 - 11.4 cm) are used in individual boats in Sri Lankan reservoirs targeting mainly two exotic cichlid species, Oreochromis mossambicus and O. niloticus , which dominate the fisheries accounting for over 80% of the landings. Although the filament characteristics and dimensions of gillnets of different mesh sizes are uniform, their mesh composition varies from boat to boat making catch samples in individual boats are under the influence of different selectivity patterns. As such, an approach is presented for constructing the overall selection curves in the sampled boats during different sampling occasions for the two cichlid fish species in the three reservoirs. For this purpose, gillnet selectivity of each mesh size was determined using Baranov-Holt method. Probabilities of capture of mesh-wise gillnet selection curves were then summed up giving weight to the contribution of each mesh size to the total number of net pieces in the sampled boat, to determine the overall gillnet selection from gillnets of all mesh sizes. The importance of the findings of the present study for length-based stock assessment methods and for imposing mesh regulations to the gillnet fisheries in reservoirs of Sri Lanka is discussed.

Recreational boating: a large unregulated vector transporting marine invasive species

Aim Recreational boating is arguably the largest unregulated vector for the introduction and spread of marine invasive species. Hull fouling communities have been recognized to harbour non-indigenous species (NIS), but presence should not be equated with transport. In this study, we characterize the presence of NIS in hull fouling communities, determine if host vessels transport these species and evaluate the importance of recreational boating as a vector for introduction and spread. Location Coastal British Columbia (BC), Canada. Methods Dive surveys in BC marinas were conducted to record the presence of NIS and to estimate their per cent cover. In addition, a boater questionnaire survey was used to determine common travel and maintenance practices. These results were combined to investigate the potential for recreational boats to transport NIS. Results Nine NIS, including the highly invasive ascidians Styela clava and Botrylloides violaceus, and the macroalga Sargassum muticum, were found in hull fouling communities on recreational boats. Overall, per cent cover was generally low; however, niche areas were commonly fouled, even on active and otherwise clean boats. Fouling of niche areas was not related to either antifouling paint age or travel frequency, and fouling levels were highly variable among individual boats both within marinas and across regions. Main conclusions Recreational boating is a major vector contributing to the spread of marine invasive species. Our results indicate that recreational boats represent a high-risk vector both for primary introduction and secondary spread of marine NIS and should be subject to vector management regulations.

In Response to Pedersen's ‘A Clench-Fastened Boat in Kerala’: a revealing boat narrative not a ‘new’ type of boat

This article discusses Pedersen’s interpretation of a boat observed in the backwaters of Kerala, south-western India in May 2003 as a previously undocumented vessel-type: a clench-fastened boat (2010). It argues that the boat he describes is not a new boat type but suggests instead that it reflects the flexibility and pragmatism of boat-building and repair in Kerala’s backwaters, where a plurality of fastening techniques and methods of construction are regularly employed in the construction of individual boats. The paper suggests the boat is a product of the dynamism, continued strength and adaptability, of Kerala’s ‘traditional’ backwater boat-building industry. In addition, it highlights some of the pitfalls of interpreting boats through construction features alone.

Occupational risks, safety and masculinity: Newfoundland fish harvesters' experiences and understandings of fishery risks

There is no single, objective place from which to assess risk, and the best way to assess and minimise risk is through seeking input from a variety of different knowledge agents focusing on different sources and dimensions of risk and using multiple methodologies. This paper draws on Wynne's work on constructivist-realism and on the feminist literature on masculinity to examine fish harvesters' understandings and experiences of risk and safety in the province of Newfoundland and Labrador on Canada's east coast. Using data drawn from focus groups, phone interviews and from individual boat tours with Newfoundland fish harvesters, it is argued that their understandings and practices of risk and safety are dynamic and that this dynamism reflects the intersection of everyday requirements to get the job done in what are often uncertain and constrained circumstances associated with the interacting and changing regulatory, industrial and environmental contexts in which this work is done. From this perspective, while quantifying fisheries risks in terms of fatality, accident or Search and Rescue incident rates is important, the inclusion of fish harvesters' experiences and related safety knowledge in research and policy-development designed to reduce risk is imperative. The view from the deck of the vessel and fish harvesters' experiences on the water not only informs their observations and interpretations of risk but offer potential insights into risk and into expert claims about risk that should be taken into account when trying to understand fishing risk and improve safety.

RESTRICTING FISHING: A SOCIO-ECONOMIC IMPACT ASSESSMENT OF ARTISANAL SHARK AND RAY FISHING IN CILACAP

Catches of shark and ray are considered important in Indonesian fisheries. Anecdotal evidence suggests that these fisheries may be over-exploited, but catches of shark and ray may be critical to their economic viability and the welfare of fishing communities dependent on them. Through a case study in Cilacap, Central Java, this paper assesses the potential economic and social impact on fishers and their households of restrictions on shark and ray catch. It reveals that shark and ray rep resent a minor component of this fishery's total catch, so the likely impact on the cash profitability of individual boats and the cash flow of fishing households would be minimal. However, inclusion of non-monetary costs in the analysis reveals that net returns to boat owners are negative. Shark and ray catch reductions will add further losses, and downstream activities such as processing of shark and ray products could imply an amplified aggregate impact.

AN INDIVIDUAL-BASED FISHERY MODEL AND ASSESSING FISHERY STABILITY

ABSTRACT. The stability of a fishery system was investigated using two forms of a stochastic computer simulation model that was individually based in terms of the fishing boats. Fish catch was partitioned among boats according to two catch processes: an unranked process in which all boats had equal ability to catch fish and a ranked catch model in which a boat's ability to catch fish depended on its wealth. Stock size, total catch, fleet size and individual boat wealth were modeled over a series of years. In the unranked catch model the fish stock size and fleet size were significantly more variable than in the ranked catch model.

Human error in recreational boating

Each year over 600 people die and more than 4000 are reported injured in recreational boating accidents. As with most other accidents, human error is the major contributor. U.S. Coast Guard reports of 3358 accidents were analyzed to identify errors in each of the boat types by which statistics are compiled: auxiliary (motor) sailboats, cabin motorboats, canoes and kayaks, house boats, personal watercraft, open motorboats, pontoon boats, row boats, sail-only boats. The individual errors were grouped into categories on the basis of similarities in the behavior involved. Those presented here are the categories accounting for at least 5% of all errors when summed across boat types. The most revealing and significant finding is the extent to which the errors vary across types. Since boating is carried out with one or two types of boats for long periods of time, effective accident prevention measures, including safety instruction, need to be geared to individual boat types.

MODE-EMERGENCE IN THE SYNCHRONIZED SAILING OF CAMPHOR BOATS

The synchronized self-motion of three camphor boats was investigated on a circular water route as a simple example of mode-emergence. When three camphor boats were floated on the surface of water in a circular route in the same direction, various kinds of synchronization could be produced by changing the inherent velocities of the boats. The essential features of synchronization were reproduced by a numerical calculation regarding the distances among three camphor boats, which changed the driving forces of the individual boats. We believe that the present results may be useful for developing novel experiments with vector processes and mode-switching.

Implications of differences in technical efficiency of fishing boats for capacity measurement and reduction

Capacity measurement and reduction is a major international issue to emerge in the new millennium. However, there has been limited assessment of the success of capacity reduction schemes (CRS). In this paper, the success of a CRS is assessed for a European fishery characterised by differences in efficiency levels of individual boats. In such a fishery, given it is assumed that the least efficient producers are the first to exit through a CRS, the reduction in harvesting capacity is less than the nominal reduction in physical fleet capacity. Further, there is potential for harvesting capacity to increase if remaining vessels improve their efficiency.

The red shrimp Aristeus antennatus (Risso, 1816) fishery and biology in the Balearic Islands, Western Mediterranean

The present study updates the information on the red shrimp fishery in the waters of the Balearic Islands in the middle of the Western Mediterranean, from its beginning to the present. Also, the development of the fishery and the biology of the shrimp population exploited from 1992 to 1997 is analysed. The red shrimp ( Aristeus antennatus) is one of the most important resources of bottom trawling in the Balearic Islands. It is fished on the slope between depths of 400 to 800 m. In biomass, it represents an average of 5% of the overall catches, but its economic value is 30% of the total earnings of the fishery. From 1948 to 1997, the landing increased at an average rate of 3405 kg per year. However, this increment was not constant for the whole period, and has been decreasing in the last five years. The engine power of boats fishing on the slope of the Balearic Islands doubled from the 1970s until the end of the study. At the moment, the number of fishing units is decreasing, although the power of the individual boats is increasing continuously. The trawl yields varied between 3 and 14 kg/h. The highest yields occurred in winter and spring. The decline of the sizes at first capture in 1997 and the increase of juveniles in the catches can be interpreted as a change in the fishery strategy, which has increased the exploitation effort on the small sizes.

Development of management measures for the groundfish fishery in Atlantic Canada: A case study of the Nova Scotia inshore fleet

Subsequent to extension of fishery jurisdiction in 1977 it was Canadian policy to favour the inshore sector in rehabilitation of the Canadian groundfish fishery. Catch allocation, limited entry licensing and vessel replacement policies were implemented, which at first allowed and then increasingly attempted to limit inshore fleet expansion, which was being encouraged through financial assistance programmes. New regulatory authorities wer obtained to deal with the increasingly difficult task of limiting annual harvests to catch quota levels. A 1986 study concluded that the licensed capacity of the Nova Scotia inshore fleet was approximately four times that required to exploit the resource at target levels. As a result of a government task force report released in January 1990, substantial changes were made in the control of fishing by inshore fleets, including establishment of an individual boat catch quota system for some sectors. This article documents the regulatory actions taken to date to control inshore fleet development and annual fishing activities, and the responses of fishermen to these, as a possible guide to the implementation of new approaches.

Tax Versus Quota Regulation: A Stochastic Model of the Fishery

AbstractIn a deterministic setting, it has been demonstrated that taxes and quotas can be equivalent regulatory instruments and that both can in principle induce an optimal allocation of resources in markets where externalities are problematic. In this paper we consider growth, harvest, and demand uncertainty within the context of Canada's Pacific halibut fishery and find that, while taxes remain the preferred instrument, the welfare losses arising from the use of individual boat quotas are minor.

A decision support simulation model for design of fast patrol boats

This paper gives an outline of a simulation model that will provide decision support in the complex process of designing a new generation fast patrol boats. Decision support in this context implies evaluating the effectiveness of different concepts for fast patrol boats in their primary role. The model addresses effectiveness issues at the tactical level, emphasizing a realistic and flexible representation of operations of a fast patrol boat squadron rather than individual boat operations. Main elements of the model are presented in some detail.

China's War With Vietnam, 1979: Issues, Decisions and Implications.

Unprecedented in scale and casualties, the brief Sino-Vietnamese war in 1979 was the bloodiest military conflict in the fraternal communist world. Why did the People's Republic of China and Vietnam, two comrades and brothers, engage in such a tragic war? This is one of the central questions Professor Chen attempts to answer in this in-depth discussion of that war-from its origins to its current international implications.The author offers an important framework for the analysis of Chinese military-diplomatic policy, traces the causes that led to the outbreak of the war, examines the process of the war decisionmaking in Beijing, explains why the war was called Deng Xiaoping's War, and observes the development of the reactions of the United States, the Soviet Union, and the ASEAN nations. Professor Chen's discussion of the effect of the Vietnam War's legacy on the Sin-Vietnamese struggle adds to the depth of the analysis. Professor Chen also broadly explores the questions: Did aid from the PRC during the three decades from 1949 to 1978 assist or betray the Vietnamese revolution? How significant were the Kampuchean and Soviet factors in Beijing's decision on war against Vietnam? How did the United States, China and other countries help to resettle the Indochinese refugees? What is the future for Kampuchea? What is the possibility of Sino-Vietnamese normalization? And what is the Soviet status versus the U.S. position in the Asian-Pacific region?In addition to researching official and private documents to bring light to this shadowy topic, Professor Chen conducted numerous interviews with Asian personnel, ranging from Prince Norodom Sihanouk to individual boat people. He also made use of monitored radio broadcasts from communist and noncommunist countries.

Radiotelephone System for Harbor and Coastal Services

Radiotelephone service with harbor and coastal vessels is now being given through coastal stations in the vicinities of seven large harbors on the Atlantic and Pacific coasts with additional stations planned. The system is designed to be as simple as possible from both the technical and operating standpoints on both ship and shore. Recent developments in the shore-station design eliminates all manipulations of the controls by the technical operator. This is made possible principally because of crystal-controlled frequencies on shore and ship, a "vogad" which keeps the transmitting volume of the shore subscriber constant, and a "codan" incorporated in the shore radio receiver which will operate on signal carrier but is highly discriminatory against noise. A signaling system permits the traffic operator to call in an individual boat by dialing the assigned code which rings a bell on the particular boat called. The ship calls the shore station by turning on the transmitter. The radio signal operates the codan in the shore receiver which in turn lights a signal lamp in the traffic switchboard. Gradually the system has been taking on more and more the aspects of the wire telephone system.