Tracking migratory salmonids

The River Ribble drains into the Irish sea on the West coast of England. The estuary is approximately 20Km long, tunnel shaped, tapering from a 100m width at Preston dock to 5 km at Lytham where it enters the sea. This is a preliminary report on a study of oxygen requirements of Atlantic salmon (Salmo salar)and sea trout (Salmo trutta) in an estuary. Oxygen sending transmitters attached to fish were used to determine exposure of individuals to different dissolved oxygen concentrations as they moved in from the sea through the estuary of the River Ribble. This estuary is subject to extreme variations in dissolved oxygen concentrations. This report is based on the latest transcription and analysis of data completed in October 1983. The aim of this report is to give an overview of the work done and conclusions which are apparent at this stage

Cameras and carcasses: historical and current methods for using artificial food falls to study deep-water animals

Deep-ocean animals remain poorly understood compared to their shallow-water relatives, mainly because of the great cost and difficulty involved in obtaining reliable ecological data. This is a serious issue as exploitation of deep-water resources progresses without sufficient data being available to assess its risks and impacts. First described almost 40 years ago, the use of baited cameras was pioneered by deep-sea biologists and is now a widely used technique for the assessing patterns of animal behaviour, abundance and biodiversity. The technique provides a non-destructive and cost-effective means of collecting data, where other techniques such as trawling are difficult or impractical. This review will first describe the evolution of baited camera techniques in deep-sea research from the early deployments, through recent programs to investigate trends in animal distribution with depth, latitude, and ocean basin. In the second section the techniques used for imaging, baiting, and analysis are synthesized, with special consideration for the modeling techniques used in assessing animal abundance and biomass

The impact of deep-sea fisheries and implementation of the UNGA Resolutions 61/105 and 64/72. Report of an international scientific workshop

The scientific workshop to review fisheries management, held in Lisbon in May 2011, brought together 22 scientists and fisheries experts from around the world to consider the United Nations General Assembly (UNGA) resolutions on high seas bottom fisheries: what progress has been made and what the outstanding issues are. This report summarises the workshop conclusions, identifying examples of good practice and making recommendations in areas where it was agreed that the current management measures fall short of their target

The impact of deep-sea fisheries and implementation of the UNGA Resolutions 61/105 and 64/72. Report of an international scientific workshop, National Oceanography Centre, Southampton

The scientific workshop to review fisheries management, held in Lisbon in May 2011, brought together 22 scientists and fisheries experts from around the world to consider the United Nations General Assembly (UNGA) resolutions on high seas bottom fisheries: what progress has been made and what the outstanding issues are. This report summarises the workshop conclusions, identifying examples of good practice and making recommendations in areas where it was agreed that the current management measures fall short of their target.Peer reviewe

Expansion of fisheries in Qatar (1980-1992): Growth of an artisanal fleet and closure of a trawling company

Total fish landings in Qatar increased from 1736 t per annum in 1980 to 7845 t in 1992. Ninetythree percent of this growth was due to an increase in the artisanal fleet exemplified by increases in: (i) numbers of vessels from 174 to 422; (ii) number of fishermen from 573 to 1962; (iii) mean power from 30 to 67 kW. The Qatar National Fishing Company (QNFC) fleet of trawlers ceased operation in 1992 when market share by value of catch had declined to 4.6%. The artisanal fleet landed a greater variety of high value species. Catch per unit effort (CPUE) of the trawlers showed no signs of decline but the average was 30% of values reported during trials in the 1970s. The CPUE was highest from January to April (124.3 kg h-1) and lowest in October (100.4 kg h-1)

Areal coverage of the ocean floor by the deep-sea elasipodid holothurian Oneirophanta mutabilis: estimates using systematic, random and directional search strategy simulations

Deep-sea sediment can be markedly modified by the activities of the mobile epibenthic megafauna. Among other factors, the scale and rate of such bioturbations will be influenced by the population density, as well as by the pattern and speed of movement of members of such a faunal group. Any attempt to obtain an estimate of the effects of the activity of such groups on the sediment is accompanied by a number of assumptions about their individual mode of movement. We examined the degree to which these estimates depend on the assumed mode of motion. Speed and behaviour data were recovered from a free-vehicle camera for the elasipodid holothurian Oneirophanta mutabilis, a dominant component of the mobile invertebrate megafauna on the Porcupine Abyssal Plain (PAP), northeast Atlantic. Using these data, we developed a number of simulations to determine the time taken by the PAP population of O. mutabilis to cover 50% of the sediment area (t50%) by differing ranging strategies. At a hypothetical population density of 27.78 indiv. × 10−3 m−2 using a systematic search, t50% is 12 days whereas for a random ranging strategy, t50% is 17 years. A simulation incorporating observed distributions of speed and angles of turn, hence approximating the actual behaviour of the holothurian, issued a t50% of 9.6 years. The behaviour of the animal is shown to have a profound effect on areal coverage times and consequent rates of bioturbation. Simply multiplying mean speed by swath width is shown to be too simplistic an approach

In situ comparison of activity in two deep-sea scavenging fishes occupying different depth zones

The activity of two scavenging deep–sea fishes occupying the same niche in overlapping depth zones were compared by in situ measurements of swimming speeds, tail–beat frequencies and by arrival time at baits. At 4800 m on the Porcupine Abyssal Plain, the grenadier Coryphaenoides (Nematonurus) armatus was the dominant scavenger, arriving at baits after 30 min, and swimming at relatively slow speeds of 0.17 body lengths (BL) sec-1. At 2500 m in the relatively food rich Porcupine Seabight both C. (N.) armatus and the blue–hake, Antimora rostrata, were attracted to bait, but A. rostrata was always the first to arrive and most of the bait was consumed before the C. (N.) armatus arrived. A. rostrata swam at mean speeds of 0.39 BL sec−1, similar to related shallow water species at equivalent temperatures. Observations on tail–beat frequency from video sequences confirmed the greater activity of A. rostrata. The data indicate that, given sufficient food supply, high pressure and low temperature do not limit activity levels of demersal deep–sea fishes. Low activity of C. (N.) armatus is an adaptation to poor food supply in the abyss, where these fishes dominate, but prevents it competing with the more active A. rostrata in shallower depths

Depth zonation and latitudinal distribution of deep-sea scavenging demersal fishes of the Mid-Atlantic Ridge, 42 to 53°N

Scavenging fishes of the Mid-Atlantic Ridge (MAR) were investigated using a baited autonomous lander equipped with a time-lapse camera between 924 and 3420 m water depth along 3 east–west transects at 42, 51 and 53°N across the MAR. We photographed 22 taxa at bait. Community structure analysis revealed 3 main assemblages, shallow (924 to 1198 m), intermediate (1569 to 2355 m) and deep (2869 to 3420 m), dominated by 3 species, Synaphobranchus kaupii, Antimora rostrata and Coryphaenoides (Nematonurus) armatus, respectively. Abyssal species in the axial valley region were C. armatus, Histiobranchus bathybius and Spectrunculus sp. Compared with continental margin regions A. rostrata were abundant and grew to a large size in the 2 northern transects, whereas S. kaupii were reduced in abundance and maximum depth of occurrence. The size, abundance and depth distribution of C. armatus was consistent with the hypothesis that these fish are part of a population mixing freely across the deep North Atlantic Basin. Temperature and latitude influenced distribution. (1) Five taxa were found only in the southern transect: Pseudotriakis microdon, Centroscymnus coelolepis, Simenchelys parasitica, Anguilliformes sp. and Lepidion 1 sp. (guentheri?). (2) Eight taxa were confined to the 2 northern transects: Bathyraja sp., Coryphaenoides 1 sp. (leptolepis?/mediterraneus?), Coryphaenoides 2 sp. (leptolepis?/mediterraneus?), Macrourus berglax, young macrourids, Lepidion 2 spp. (schmidti?), Anarhichas denticulatus and an unidentified zoarcid (Lycodonus n. sp.?/Lycenchelys alba?). (3) Eight species were ubiquitous across all 3 transects: Etmopterus princeps, Hydrolagus affinis, H. bathybius, S. kaupii, C. armatus, A. rostrata, Lepidion eques and Spectrunculus 1 sp.

Scavenging interactions between the arrow tooth eel Synaphobranchus kaupii and the Portuguese dogfish Centroscymnus coelolepis

A scavenging interaction between the arrow tooth eel Synaphobranchus kaupii and the Portuguese dogfish Centroscymnus coelolepis, both ubiquitous components of fish assemblages at bathyal depths, was observed. Using a baited camera between 1297 and 2453 m in the eastern Atlantic Ocean continental slope, it was shown that despite consistently rapid arrival times of S. kaupii (2 h before feeding, thus contradicting conventional scavenging assumptions in the presence of a food fall