scholarly journals Limited mid-water scavenging of trawl discards

2003 ◽  
Vol 83 (4) ◽  
pp. 731-734 ◽  
Author(s):  
Karim Erzini ◽  
Pedro Monteiro ◽  
Artur Araújo ◽  
Margarida Castro
Keyword(s):  
Water Column ◽  
Deep Water ◽  
Small Fish ◽  
Sea Birds ◽  
Trawl Fishing ◽  
Southern Portugal ◽  
Catch Rates ◽  
Electric Fishing ◽  
Scavenging Rates

The consumption or scavenging of fish in the water column at depths from 75 to 275 m in Algarve (southern Portugal) trawl fishing grounds was evaluated. Longlines were used to suspend baits throughout the water column while electric fishing reels were used to simulate sinking discards. Eighteen species were caught, with higher catch rates near the surface than near the bottom. However, scavenging rates were generally highest near the bottom and lowest in the middle of the water column. At depths less than 100 m the majority or all the fish were scavenged throughout the water column, while at depths greater than 200 m most of the fish were untouched after periods of time greater than would be required for them to sink to the bottom. Since other studies have shown that most small fish discards are scavenged at the surface by sea birds and most of the discarded species that sink are either too large or not attractive to pelagic predators, these results suggest that mid-water scavenging of trawl discards in deep water is relatively unimportant.

scholarly journals Preliminary results on the use of semi-floating shrimp traps for the striped soldier shrimp, Plesionika edwardsii (Crustacea: Decapoda: Pandalidae), off the Algarve coast (southern Portugal)

2018 ◽  
Vol 82 (S1) ◽  
pp. 209
Author(s):  
Moritz Eichert ◽  
Aida Campos ◽  
Paulo Fonseca ◽  
Victor Henriques ◽  
Margarida Castro
Keyword(s):  
Environmental Impact ◽  
Deep Water ◽  
Bottom Trawl ◽  
Marine Strategy Framework Directive ◽  
Precautionary Approach ◽  
Preliminary Results ◽  
Product Value ◽  
Fisheries Policy ◽  
Southern Portugal ◽  
Experimental Survey

The present study provides an account of an experimental survey aiming at the evaluation of the catchability of the striped soldier shrimp, Plesionika edwardsii, using semi-floating shrimp traps off the Algarve coast (southern Portugal). Currently, this species is not targeted by the crustacean bottom trawl fleet, and preliminary results on product value suggest that this may become an economically viable new fishery. Preliminary results suggest that this fishery could contribute to the diversification of fixed gears of low environmental impact targeting deep-water crustaceans, in agreement with the objectives of both the Marine Strategy Framework Directive and the reformed Common Fisheries Policy. However, potential spatial conflicts with trawling, the unknown size of the resource and a necessary precautionary approach may limit the number of licences that can be granted.

scholarly journals The response of water column and sedimentary environments to the advent of the Messinian salinity crisis: insights from an onshore deep-water section (Govone, NW Italy)

2020 ◽  
pp. 1-17
Author(s):  
Mathia Sabino ◽  
Francesco Dela Pierre ◽  
Marcello Natalicchio ◽  
Daniel Birgel ◽  
Susanne Gier ◽  
...  
Keyword(s):  
Water Column ◽  
Deep Water ◽  
Bottom Layer ◽  
Messinian Salinity Crisis ◽  
Sedimentary Environments ◽  
Water Column Stratification ◽  
Stratigraphic Architecture ◽  
Spatial Changes ◽  
Oxygen Stable Isotope ◽  
Nw Italy

Abstract During Messinian time, the Mediterranean underwent hydrological modifications culminating 5.97 Ma ago with the Messinian salinity crisis (MSC). Evaporite deposition and alleged annihilation of most marine eukaryotes were taken as evidence of the establishment of basin-wide hypersalinity followed by desiccation. However, the palaeoenvironmental conditions during the MSC are still a matter of debate, chiefly because most of its sedimentary record is buried below the abyssal plains of the present-day Mediterranean Sea. To shed light on environmental change at the advent and during the early phase of the MSC, we investigated the Govone section from the Piedmont Basin (NW Italy) using a multidisciplinary approach (organic geochemical, petrographic, and carbon and oxygen stable isotope analyses). The Govone section archives the onset of the crisis in a succession of organic-rich shales and dolomite-rich marls. The MSC part of the succession represents the deep-water equivalent of sulphate evaporites deposited at the basin margins during the first phase of the crisis. Our study reveals that the onset of the MSC was marked by the intensification of water-column stratification, rather than the establishment of widespread hypersaline conditions. A chemocline divided the water column into an oxygen-depleted, denser and more saline bottom layer and an oxygenated, upper seawater layer influenced by freshwater inflow. Vertical oscillations of the chemocline controlled the stratigraphic architecture of the sediments pertaining to the first stage of the MSC. Accordingly, temporal and spatial changes of water masses with different redox chemistries must be considered when interpreting the MSC event.

Trawl Fishing in the Tropical Atlantic: Catch-rates and Composition

Nature ◽  
1961 ◽  
Vol 192 (4803) ◽  
pp. 620-621 ◽  
Author(s):  
R. H. LOWE ◽  
ALAN R. LONGHURST
Keyword(s):  
Tropical Atlantic ◽  
Trawl Fishing ◽  
Catch Rates

scholarly journals length at first maturity of two species of lantern sharks (etmopterus spinax and etmopterus pusillus) off southern portugal

2005 ◽  
Vol 85 (5) ◽  
pp. 1163-1165 ◽  
Author(s):  
rui coelho ◽  
karim erzini
Keyword(s):  
Deep Water ◽  
Shark Species ◽  
Fishing Mortality ◽  
Portuguese Coast ◽  
Southern Portugal ◽  
First Maturity ◽  
Late Maturation ◽  
Size At First Maturity

etmopterus spinax and etmopterus pusillus are captured in large quantities in some deep-water fisheries along the portuguese coast and are always discarded. specimens were collected from february 2003 to may 2004 from deep-water fisheries and classified as mature or immature. maturity ogives were fitted and size at first maturity estimated for each sex of each species. both species are late maturing, with the maturity sizes varying between 75% and 87% of the maximum observed sizes, depending on species and sex. for both species, females tended to mature at and grow to larger sizes than males. the late maturation of these deep-water shark species makes these populations extremely vulnerable to increasing fishing mortality.

Potential of a trap-fishery for deep-water rock lobster Palinurus delagoae off South Africa

1997 ◽  
Vol 48 (8) ◽  
pp. 993 ◽  
Author(s):  
J. C. Groeneveld ◽  
A. C. Cockcroft
Keyword(s):  
South Africa ◽  
South African ◽  
Deep Water ◽  
Linear Models ◽  
Depth Interval ◽  
Suitable Habitat ◽  
Rock Lobster ◽  
Experimental Phase ◽  
Trap Fishery ◽  
Catch Rates

An experiment to investigate the potential of a trap-fishery for deep-water rock lobster Palinurus delagoae was conducted off the east coast of South Africa between 1994 and 1996. The 75–425 m depth interval between 27°S and 32°S was stratified according to depth and latitude, and three regions (North, Central and South) were sampled systematically over the three years. Sampling by commercial vessels operating long-lines and traps included an experimental phase (fixed fishing positions) and a commercial phase (no restriction on fishing location). Generalized linear models were used to investigate the influence of year, region, sampling phase, month and soak time. Sampling phase was significant, with traps set during the commercial phase catching more than those set in the experimental phase. The effect of soak time on catch rates was not significant. The almost-50% decrease in the combined abundance index combined with a marked decrease in mean lobster size over the study period suggests a relatively low fisheries potential for this species in South African waters; this may be attributable to the relative scarcity of suitable habitat in the area.

Elevated turbidity and dissolved manganese in deep water column near 10°47’S Central Indian Ridge: studies on hydrothermal activities

2020 ◽  
Vol 40 (5) ◽  
pp. 619-628 ◽  
Author(s):  
Durbar Ray ◽  
K. A. KameshRaju ◽  
A. Srinivas Rao ◽  
L. SuryaPrakash ◽  
Abhay V. Mudholkar ◽  
...  
Keyword(s):  
Water Column ◽  
Deep Water ◽  
Central Indian Ridge ◽  
Indian Ridge ◽  
Hydrothermal Activities

scholarly journals Concept Tests for a New Wire Flying Vehicle Designed to Achieve High Horizontal Resolution Profiling in Deep Water

2011 ◽  
Vol 28 (12) ◽  
pp. 1657-1671 ◽  
Author(s):  
Chris Roman ◽  
Dave Hebert
Keyword(s):  
Water Column ◽  
Deep Water ◽  
Free Stream ◽  
Horizontal Resolution ◽  
Vehicle Body ◽  
Scale Model ◽  
Stream Velocity ◽  
Wide Range ◽  
High Horizontal Resolution ◽  
Ship Speed

Abstract Efficiently profiling the water column to achieve both high vertical and horizontal resolution from a moving vessel in deep water is difficult. Current solutions, such as CTD tow-yos, moving vessel profilers, and undulating tow bodies, are limited by ship speed or water depth. As a consequence, it is difficult to obtain oceanographic sections with sufficient resolution to identify many relevant scales over the deeper sections of the water column. This paper presents a new concept for a profiling vehicle that slides up and down a towed wire in a controlled manner using the lift created by wing foils. The wings provide a novel low-power method of propulsion along the cable by using the free stream velocity of the wire moving through the water in similar fashion to a sailboat sailing up wind. Scale model tests show a wide range of achievable profiling glide slopes for tow cable angles between vertical and 45°, and effective isolation of cable strum vibration from the towed vehicle body. The concept is not depth limited and will offer two-dimensional resolution that meets or exceeds current undulating tow bodies over the full water column. Additionally, this system could be used simultaneously with many other deep towed instrument packages to produce complementary datasets.

Feeding habits of the velvet belly lanternshark Etmopterus spinax (Chondrichthyes: Etmopteridae) off the Algarve, southern Portugal

2006 ◽  
Vol 86 (4) ◽  
pp. 835-841 ◽  
Author(s):  
João Neiva ◽  
Rui Coelho ◽  
Karim Erzini
Keyword(s):  
Deep Water ◽  
Foraging Behaviour ◽  
Prey Size ◽  
Feeding Habits ◽  
Feeding Strategy ◽  
Stomach Contents ◽  
Prey Composition ◽  
Southern Portugal ◽  
Meganyctiphanes Norvegica ◽  
Diet Shifts

Etmopterus spinax is one of the most abundant predators of the upper continental slope off the Algarve (southern Portugal), where it is captured in large quantities in deep-water fisheries. The feeding habits of E. spinax off the Algarve were investigated through the analysis of stomach contents of 376 individuals. Prey composition was described and maturity, sex and size related variations in the diet analysed. The overall diet of E. spinax suggested a fairly generalized benthopelagic foraging behaviour primarily tuned to pelagic macroplankton/microneckton, teleost fish and cephalopods. Sex and maturity related differences in the diet were not significant. Two main ontogenic diet shifts were observed at about 17 and 28 cm total length. Small and medium sized immature sharks had a diet dominated by eurybathic crustaceans, chiefly Meganyctiphanes norvegica and Pasiphaea sivado. Larger individuals consumed more teleosts and cephalopods, in part associated with scavenging as a new feeding strategy. With increasing shark size the diet diversified both in terms of resources exploited and prey size.

THE NET ENVIRONMENTAL BENEFIT OF A SUCCESSFUL DISPERSANT OPERATION AT THE SEA EMPRESS INCIDENT

1997 ◽  
Vol 1997 (1) ◽  
pp. 185-194 ◽  
Author(s):  
Tim Lunel ◽  
Jan Rusin ◽  
Nick Bailey ◽  
Chris Halliwell ◽  
Louise Davies
Keyword(s):  
Water Column ◽  
Monitoring Program ◽  
Environmental Benefit ◽  
Sea Birds ◽  
Sufficient Detail ◽  
Timely Fashion ◽  
Spill Site ◽  
Set Up

ABSTRACT The monitoring of oil concentrations in the water column during a dispersant operation carried out at the Sea Empress incident has clearly demonstrated that, although a monitoring program should not be viewed as a prerequisite to response (since the spill site may be too remote to allow monitoring to be set up for the start of the response operation), if monitoring is planned as part of the response, it enables operations to be executed efficiently. The estimates put forward in this paper indicate that the targeted use of dispersants probably prevented 57,000 to 110,000 tons of emulsion from impacting the shoreline and potentially resulting in greatly increased impacts on sea birds, coastal waders, intertidal vertebrates and invertebrates, and amenity areas. The paper shows that these benefits outweighed the potential disadvantages associated with elevated oil concentrations in the water column. The Sea Empress is the first incident that has been monitored in a timely fashion in sufficient detail. The monitoring program demonstrated that the use of dispersants resulted in a net environmental benefit at the Sea Empress incident.

scholarly journals Evidence of old carbon in the deep water column of the Panama Basin from natural radiocarbon measurements

1998 ◽  
Vol 25 (10) ◽  
pp. 1733-1736 ◽  
Author(s):  
Ellen R. M. Druffel ◽  
Sheila Griffin ◽  
Susumu Honjo ◽  
Steven J. Manganini
Keyword(s):  
Water Column ◽  
Deep Water
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