DOCSLIB.ORG

Stepped‐Oblique Midwater Trawling As an Assessment Technique For

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Stepped‐Oblique Midwater Trawling As an Assessment Technique For North American Journal of Fisheries Management 11:167-176. 1991 © Copyright by the American Fisheries Society 1991 Stepped-Oblique Midwater Trawling as an Assessment Technique for Rainbow Smelt RICHARD A. KIRN* AND GEORGE W. LABAR School of Natural Resources, University of Vermont Burlington, Vermont 05405, USA Abstract.—Discrete-depth midwater trawling for rainbow smelt Osmerus mordax at night in Lake Champlain revealed a delayed vertical migration of smaller fish and size partitioning vertically within the water column. These behavioral observations led to the development and evaluation of a nighttime stepped-oblique midwater trawling technique. This latter method proved effective in obtaining large catches of rainbow smelt (mean catch per unit of effort [CPUE], 215-655 fish/ 55-min trawl) and provided estimates of relative abundance with reasonable precision (CPUE ± 13-50% from June through October), as well as estimates of length and age distributions unbiased by vertical migration behavior. Rainbow smelt Osmerus mordax serve as the vide information on the sexually mature portion principal forage species for stocked salmonids in of the population, limiting the value of such sur- Lake Champlain (Kirn 1986) and many other New veys for monitoring year-class dynamics. In ad- England waters (Kircheis and Stanley 1981). The dition, this approach is not feasible for waters with desirability of rainbow smelt as a food and forage significant lake-spawning populations of rainbow fish, and the relative ease with which they are smelt, such as are found in Lake Champlain (Plo- transferred to other waters, is resulting in a con- sila 1984). In recent years, hydroacoustic sampling tinually expanding distribution of this species has proven to be a reliable technique for moni- (Maydenetal. 1987). toring the abundance of pelagic fish stocks (Argyle Knowledge of forage-fish population dynamics 1982; Heist and Swenson 1983), but requires ex- is an important component of recent freshwater pensive equipment and must be integrated with salmonid introduction and restoration programs, other sampling gear to determine species com- especially in situations such as in Lake Champlain, position and obtain biological samples. where recruitment of salmonids relies almost ex- Daytime bottom and midwater trawling in Lake clusively upon hatchery production and is there- Huron indicated that discrete portions of the rain- fore independent of forage abundance. The ability bow smelt populations inhabited both the bottom to recognize fluctuations in rainbow smelt abun- and midwater during the day, and were therefore dance before predator growth is affected is partic- unavailable to a single trawling method (Argyle ularly critical given the potential for extreme vari- 1982). Observations of size partitioning among ability in the abundance of rainbow smelt, which daytime rainbow smelt distributions have been apparently is unrelated to stock size, predation, associated with bottom depth and possibly water fishing intensity, or disease (Smith 1972; Havey temperature (MacCallum and Regier 1970; Argyle 1973; Kircheis and Stanley 1981; Selgeby 1985). 1982; Plosila 1982). Length or age compositions Sampling rainbow smelt populations has been estimated under these conditions become a func- complicated by size- or age-specific seasonal dis- tion of trawling location and effort rather than a tributions (MacCallum and Regier 1970; Argyle random sample of the population at large (Argyle 1982; Plosila 1982) and diel vertical migrations 1982). (Ferguson 1965; Gray 1979; Heist and Swenson Midwater trawling at night, when diel vertical 1983). Population dynamics of Great Lakes rain- migration of rainbow smelt provides a concen- bow smelt have been assessed from spring spawn- trated, pelagic distribution, has shown promise as ing runs, during which concentrations of rainbow an effective sampling strategy. Rainbow smelt con- smelt in tributaries are vulnerable to a variety of stituted 90-99% of the nighttime pelagic fish pop- sampling gears (Luey and Adelman 1984; Frie and ulation sampled with midwater trawls in the upper Spangler 1985). These surveys, however, only pro- 50 m of Lake Superior (Heist and Swenson 1983). Nighttime midwater-trawl sampling for cisco Coregonus artedii in Lake Champlain has also 1 Present address: Vermont Fish and Wildlife De- produced large catches of rainbow smelt (G.W.L., partment, Roxbury, Vermont 05669, USA. unpublished data). 167 168 KIRN AND LABAR Considering the influences of rainbow smelt be- graduated and ranged from 20.3 cm at the head- havior on past sampling strategies, the specific ob- rope to 1.3 cm at the cod-end liner. Although this jectives of this study were to develop and evaluate net was capable of retaining some young-of-the- a nighttime midwater-trawling technique for sam- year rainbow smelt, many escaped. For this rea- pling rainbow smelt populations. Results from son, young-of-the-year fish, distinguished by size preliminary discrete-depth trawls, also presented, and transparency, were not included in data anal- led to the development of a stepped-oblique mid- yses. water-trawling technique. This technique was The net was towed at 1.1 m/s by the Vermont evaluated for consistency in estimating length and Fish and Wildlife Department's 9.4-m research age distributions and relative abundance of rain- vessel Dore. Temperature and net depth were bow smelt. The influence of the temporal and spa- monitored with an ultrasonic temperature-pres- tial movements of rainbow smelt were also eval- sure transducer attached to the port bridle near uated and used to develop an overall sampling the headrope. strategy for monitoring the population. Discrete-depth trawls.—Discrete-depth trawls were performed during June, August, and October Study Area 1984, and during June and August 1985. Prelim- Lake Champlain is a typically dimictic lake lo- inary trawls in June 1984 sampled sites in Malletts cated within a north-south, glaciated fault be- Bay and the Northeast Arm (Figure 1). Subsequent tween the Adirondack Mountains of New York trawls were confined to the Main Lake. and the Green Mountains of Vermont. Meyer and Discrete-depth trawls consisted of a series of 20- Gruendling (1979) provided a detailed account of min trawls at each of three predetermined depths: the limnology of Lake Champlain. Lake dimen- midway between the surface and the top of the sions are length, 172 km; maximum width, 19 km; metalimnion, at the top of the metalimnion, and maximum depth, 129 m; mean depth, 22 m; sur- at the bottom of the metalimnion. Because of a face area, 1,140 km2. Plosila and Anderson (1985) paucity of rainbow smelt (4% of the total catch in estimated 45% of the lake to possess deep, cold June), trawls midway between the top of the meta- water with sufficient dissolved oxygen to support limnion and the surface were replaced by trawls salmonids. 10 m below the metalimnion after June 1984. In Potash et al. (1969) described five limnologically the absence of thermal stratification, depths of 15, distinct water masses in Lake Champlain: South 25, and 35 m were sampled. All three depths were Lake, Main Lake, Malletts Bay, Northeast Arm, sampled before a second series of trawls was re- and Missisquoi Bay (Figure 1). New York and peated in sequence. Trawls conducted in June 1984 Vermont state fishery investigators have further were begun within 10 min after sunset. Trawls partitioned the lake into 15 management zones. conducted after June 1984 were generally initiated Sampling during this study concentrated on zones within 90 min after sunset. Two series of discrete- 3 A and 3B of the Main Lake (Figure 1), where the depth trawls were conducted per night except in highest densities of lake trout have been reported August 1984, when three series were conducted at (Plosila and Anderson 1985). The Main Lake ac- two of the four sites sampled, and in October 1984, counts for 82% of the entire volume and 60% of when three series were conducted at 25 and 35m. the total surface area of Lake Champlain (Potash Stepped-oblique trawls.— Stepped-oblique trawls et al. 1969). Maximum surface temperatures are were deployed at least 10 m above the lake bottom, reported to reach about 23°C, while summer hy- or to a maximum depth of 35 m. Once set, the polimnetic temperatures average 6°C (Meyer and net was fished for 5 min at each 3.3-m depth stra- Gruendling 1979). Summer stratification of the tum, in stairstep fashion, until the net reached a Main Lake is reported to generally begin in June depth of about 7 m, when it was completely re- (Meyer and Gruendling 1979). Thermal stratifi- trieved. During preliminary discrete-depth trawls cation was only observed in this study during Au- in this study and earlier work (G.W.L., unpub- gust trawl sampling, when the metalimnion had lished data) in Lake Champlain, few rainbow smelt an upper boundary at 10-12 m and a lower bound- were captured in the upper 7 m of the water col- ary ranging from 17 to 25 m. umn. Although the actual net dimensions during trawling were unknown, it was assumed that the Methods 3.3-m depth strata were sufficient to ensure that Rainbow smelt were sampled with a 5-m x 5-m the net sampled the entire water column. A rep- midwater trawl. Mesh size (stretched measure) was licate trawl was then fished along the same course MIDWATER TRAWLING FOR RAINBOW SMELT 169 FIGURE 1.—Map of Lake Champlain (left) showing water masses and fishery management zones 3 A and 3B. In the large-scale map of zone 3 A and 3B (right), the lines connecting triangles, squares, and circles indicate shallow (<45-m), intermediate (45-75-m), and deep (>75-m) trawl sites, respectively. in the opposite direction. Based on results from sured to the nearest millimeter (total length). Ad- the discrete-depth trawls, stepped-oblique trawl- ditional fish were counted.
Load more

Recommended publications
  • Conference on the Canadaian Shrimp Fishery
    ideen Size Top and Bottom Wedges 15th 1-3/4" 36th ]IL Headrope: 34'9" Polydacron Rope 3/8" Diameter Footrope: 35'7" Polyduron Rope 3/8" Diameter Chainrope: Same as Footrope Twine: Nylon Floats: Two 8" Diameter, Four 5" Diameter, Four Gill Net Floats Chain: 3/16" Dlameter 13 Links to 8" of Footrope Wood: Hard Pine Oak 1" Thick Chain Brackets 3/16" Diameter Galvanized Chain I2-^.. L- 1/2" Door Weigtt Dry: 70 Pounds 18 Linl^ 25 Links Headrope: 66' 18" Footrope: 74' ^ 16 Llnks 23 Links Floats: Twenty-two to twenty-six 8" diameter floats Rollers: 14" diametér rollers on bosom z-1 2" ^- J2-1/2" Mesh Size: 2" stretched mesh wings and bellies 1-7/8" stretched mesh extension and cod end I I II 2-1/2" 2-1/2•, FIG. 18 Semi-balloon trawl. F I G. 19 Smal I boat trawl. Mr. Bruce 273 BCF GLOUCESTER TRAWL SHRIMP HEADROPE FOOTROPE Wing 27' Wing 30.5' Wing 27' Wing 30.5' Bosom 14' Bosom 12' Total 68' Total 73' Mesh Size Top --4— tvedge Bottom T Selvedge 14' T 14' I 1 2' 21th 2' 21th + 36th 280bd Top and Bottom Twine: Polyethylene throughout except for nylon cod end Wings Floats: Twenty-four 8-inch diameter floats evenly spaced Rollers: 14-inch diameter bosom rollers, 9-inch diameter i wing rouera FIG. 20 4-seam trawl. 274 CONFERENCE ON THE CANADIAN SHRIMP FISHERY FIG. 21 Shrimp pot designed in Maine showing entrance slot on top, cement ballast, bait string and bridles, pounds of shrimp were landed in two months.
    [Show full text]
  • PROGRAMME 4 - 7 July 2017 • Boardwalk Convention Centre • Port Elizabeth • South Africa
    SAMssPORT ELIZABETH 2017 THE 16TH SOUTHERN AFRICAN MARINE SCIENCE SYMPOSIUM PROGRAMME 4 - 7 July 2017 • www.samss2017.co.za Boardwalk Convention Centre • Port Elizabeth • South Africa Theme: Embracing the blue l Unlocking the Ocean’s economic potential whilst maintaining social and ecological resilience SAMSS is hosted by NMMU, CMR and supported by SANCOR WELCOME PLENARY SPEAKERS It is our pleasure to welcome all SAMSS 2017 participants on behalf of the ROBERT COSTANZA - The Australian National University - Australia Institute for Coastal and Marine Research at Nelson Mandela Metropolitan University and the city of Port Elizabeth. NMMU has a long tradition of marine COSTANZA has an H-index above 100 and >60 000 research and its institutional marine and maritime strategy is coming to citations. His area of specialisation is ecosystem goods fruition, which makes this an ideal time for us to host this triennial meeting. and services and ecological economics. Costanza’s Under the auspices of SANCOR, this is the second time we host SAMSS in PE and the transdisciplinary research integrates the study of theme ‘Embracing the blue – unlocking the ocean’s potential whilst maintaining social humans and nature to address research, policy, and and ecological resilience’ is highly topical and appropriate, aligning with Operation management issues. His work has focused on the Phakisa, which is the national approach to developing a blue economy. South Africa is interface between ecological and economic systems, at a cross roads and facing economic challenges. Economic growth and lifting people particularly at larger temporal and spatial scales, from out of poverty is a priority and those of us in the ‘marine’ community need to be part small watersheds to the global system.
    [Show full text]
  • FISHERIES RESEARCH REPORT NO. 173, 2008 Evaluation of The
    FISHERIES RESEARCH REPORT NO. 173, 2008 Evaluation of the effectiveness of reducing dolphin catches with pingers and exclusion grids in the Pilbara trawl fishery Final FRDC Report – Project 2004/068 P.C. Stephenson and S. Wells Australian Government Fisheries Research and Development Corporation Fisheries Research Division Western Australian Fisheries and Marine Research Laboratories PO Box 20 NORTH BEACH Western Australia 6920 Correct citation: Stephenson, P. C. and Wells, S. (2006). Evaluation of the effectiveness of reducing dolphin catches with pingers and exclusion grids in the Pilbara trawl fishery. Final report to Fisheries Research and Development Corporation on Project No. 2004/068. Fisheries Research Report No. 173, Department of Fisheries, Western Australia, 44p. Published by Department of Fisheries, Western Australia. March 2008. ISSN: 1035 - 4549 ISBN: 1 877098 98 1 Enquiries: WA Fisheries and Marine Research Laboratories, PO Box 20, North Beach, WA 6920 Tel: +61 8 9203 0111 Email: [email protected] Website: http://www.fish.wa.gov.au ABN: 55 689 797 771 Publications may be accessed through this website. © Fisheries Research and Development Corporation and Department of Fisheries, Western Australia 2007. This work is copyright. Except as permitted under the Copyright Act 1968 (Cth), no part of this publication may be reproduced by any process, electronic or otherwise, without the specific written permission of the copyright owners. Neither may information be stored electronically in any form whatsoever without such permission. The Fisheries Research and Development Corporation plans, invests in and manages fisheries research and development throughout Australia. It is a statutory authority within the portfolio of the federal Minister for Agriculture, Fisheries and Forestry, jointly funded by the Australian Government and the fishing industry.
    [Show full text]
  • Fishing Gear Types Single Boat Midwater Otter Trawls
    Food and Agriculture Organization of the United Nations for a world without hunger Fisheries Division Fishing Gear Types Single Boat Midwater Otter Trawls Midwater Otter Trawls ISSCFG code: 03.21 – standard abbreviation: OTM Characteristics Overview A midwater otter trawl is a cone-shaped net which is towed in mid-water. It consists of a cone- shaped body, normally made of four panels, ending in a codend and the net has lateral wings extending forward from the opening. The horizontal opening is maintained by otter boards. Floats and/or sailkites on the headline and weights on the groundline provide for the vertical opening. Large modern midwater trawls are rigged in such a way that the weights in front of and along the groundline provide for the vertical opening of the trawl. The cable transmitting acoustic signal form the net sonde might also provide a lifting force that maximize the vertical trawl opening. To reduce the resistance of the gear and achieve a large opening, the front part of the trawls are usually made from very large rhombic or hexagonal meshes. The use of nearly parallel ropes instead of meshes in the front part is also a common design. The largest mesh sizes used so far are 128 m and, on modern large midwater trawls, approximately three quarters of the length of the trawl is made with mesh sizes above 400 mm. Accessory Equipment Hydrodynamic designed otter boards are used for midwater trawling. The fishing depth is usually controlled by means of a netsounder (netsonde) or depth recorders. As for other types of Trawls, catch sensors can be installed in the codend to give information about the amount of caught fish.
    [Show full text]
  • Volume III of This Document)
    4.1.3 Coastal Migratory Pelagics Description and Distribution (from CMP Am 15) The coastal migratory pelagics management unit includes cero (Scomberomous regalis), cobia (Rachycentron canadum), king mackerel (Scomberomous cavalla), Spanish mackerel (Scomberomorus maculatus) and little tunny (Euthynnus alleterattus). The mackerels and tuna in this management unit are often referred to as ―scombrids.‖ The family Scombridae includes tunas, mackerels and bonitos. They are among the most important commercial and sport fishes. The habitat of adults in the coastal pelagic management unit is the coastal waters out to the edge of the continental shelf in the Atlantic Ocean. Within the area, the occurrence of coastal migratory pelagic species is governed by temperature and salinity. All species are seldom found in water temperatures less than 20°C. Salinity preference varies, but these species generally prefer high salinity. The scombrids prefer high salinities, but less than 36 ppt. Salinity preference of little tunny and cobia is not well defined. The larval habitat of all species in the coastal pelagic management unit is the water column. Within the spawning area, eggs and larvae are concentrated in the surface waters. (from PH draft Mackerel Am. 18) King Mackerel King mackerel is a marine pelagic species that is found throughout the Gulf of Mexico and Caribbean Sea and along the western Atlantic from the Gulf of Maine to Brazil and from the shore to 200 meter depths. Adults are known to spawn in areas of low turbidity, with salinity and temperatures of approximately 30 ppt and 27°C, respectively. There are major spawning areas off Louisiana and Texas in the Gulf (McEachran and Finucane 1979); and off the Carolinas, Cape Canaveral, and Miami in the western Atlantic (Wollam 1970; Schekter 1971; Mayo 1973).
    [Show full text]
  • Marine Fisheries Information Service
    MARINE FISHERIES ICAR INFORMATION SERVICE No. 141 JANUARY - FEBRUARY - MARCH 1996 ^«r'^"^W W^9?=fti^f9l' TI^ TECHNICAL AND f«r?rin: 3t^»T«ro^ EXTENSION SERIES ^^Icr Fr«f^ TTif^Fcr^ CENTRAL MARINE FISHERIES H^AUW ^FCIW RESEARCH INSTITUTE ^f?7, VflTfT COCHIN, INDIA INDIAN COUNCIL OF AGRICULTURAL RESEARCH COASTAL FISHERIES AND AQUACULTURE MANAGEMENT IN THE EAST COAST OF INDIA* M. Devaraj, R. Paul Raj, E.Vlvekanandan, K. Balan, R. SathiadhasandM. Srinath Centred Marine Fisheries Research Institute, Cochin-682 014 I COASTAL FISHERIES MANAGEBIENT decade the marine fish production from the east The east coast of India has s shore line of 2,581 coast has Increased from 0.41 million tonnes km and has an EEZ area of 5,61,388 sq. km. in (1985) to 0.69 million tonnes (1994) {Fig.2). In the Bay of BengEil. The continental shelf is 1994, Tcunll Nadu and Pondicherry, Andhra 1,18,950 sq. km (Table I). The inshore area (upto Pradesh, Orlssa and West Bengal contributed 50 m depth), which forms 56% of the continental 59.9, 24.3, 6.9 and 8.9% respectively to the total shelf, is being intensively exploited using different marine fish production along the east coast. types of crafts and gears. During the past one TABLE 1. Geographical profile of the east coast of India Peirameters West Orissa Andhra Tamil Nadu Total Bengal Pradesh & Pondicherry Length of 1 157 480 974 970 2,581 coast (km) ' Area (xOOOha) upto 50m 994 1,707 1,661 2,326 6,688 51-200m 1,292 656 1,443 1,816 5,207 Total 2286 2363 3104 4142 11895 Growth of fishing activity i.
    [Show full text]
  • Boat Conference Organized by the U.N
    Copiesavellshie from: SeeGrant Extension Program 6022 MoCartyHall Universityof Florida Gslnssvlila,F I.3281 1 PletW.SseOrant Cogsge le supportedhy awed of the Officeof SeeOrant, NationalOceania aad AtrnoepherieAdmlnletradon, U4. Depert- raentef Cetmmrm,grant nwahw NAESAA-~, underprovisions of the Natkmef8ee GrantCogege and ProgramsAot of 1888. This hdenaatlaals pehlldtedhy the SeeOrant Eatenekm Proipam wideh funatlons as ~ componentof the Florida CooperativeEatenslon Ssrvtse. JehuT. ggaeste,dom, In mmduetlngCoeperadve Extension work in Agriculture.Home Eoonomies, and ggerineSeieneee. State of Fkrride.U.S. gttpartnrsntef Agrharlture,UA Qspartmentof Commerse,and Soerdeof County Commiesloasm,cooperating. printed end dlstrlhutedIn ferdsemnseof the Acts of CengrWsof Stay 8 aadJune 1 1,1814. The Florida See Orant College h anEqual Employment Opportunity-Affirme- ~ eeAetkm employeraatharlmd m 'yrow4h~h, edaoatloaalkrformadon and other earvtaeeonly to individualsand InstNutlomthat ~ aoettenwithout Nacrd ta ress,eaktr, eea, or nationalorigin. I NTERNATIQNAL CONFERENCE DN DESIGN, CONSTRUCTION,AND OPERATIONOF COMMERCIAL F I SHING VESSELS Sponsored By: Florida Sea Grant College Program Society of Naval Architects and Marine Engineers, Southeast Section Florida Institute of Technology College of Science and Engineering: OceanEngineering Program Held At: Florida Institute of Technology Edi ted By: John C. Sainsbury Thomas M. Leahy Sea Grant Project No. IR/84-6 Grant No. NA 80AA-D-00038 Report Number 67 Florida Sea Grant College May 1985 Price: $10.00 ACKNOWLEDGEMENTS SPONSORS: Florida Sea Grant College Society of Naval Architects and Marine Engineers, Southeast Section Florida Institute of Technology, College of Engineering: OceanEngineering Program CONFERENCEGENERAL CHAIRMAN: Dr. JohnC. Sainsbury,Professor Chairman, Ocean Engineering Program, Florida Institute of Technology, Melbourne, Florida 32901, USA CDGRDI NATI NG COMMITTEE: Tom Col 't ins, Desco.
    [Show full text]
  • The New Fisherman
    WILLIAM B. McCLOSKEY, JR. THE NEW FISHERMAN Hydraulic hoses and black boxes make fishing easier, but exact a price. We took hail and spray in our faces and crouched buoy of the first crab pot: barely a minute's search monkey-style to keep pace while working the gear on for a 2-foot pink buoy hidden in rolling seas during a a pitching deck glazed with ice. The wind blew a snowstom. straight 35 knots and gusted 60. Up through the Despite the weather, we worked all night, black hydraulic block zipped a crab pot-a 7-foot-square waves that could obliterate us towering over our by 3-foot steel-framed cage. Seven hundred pounds deck; worked without stop through all the daylight empty, it would now weigh 1000 to 2500 pou~ hours and on through the next night until about 2 depending on the number of king crabs insi£ Its AM. At last, peeling off our raingear but nothing else, trip up from the seafloor 60 fathoms below took we groaned to our bunks. about a minute. The pot surfaced in a froth of purple By the first grey light, the skipper had the wheel crab shapes and water. We braced it at the rail again. He slowed the engine, a standard signal. Our waiting for the proper boat motion, and swung it fishermen's discipline responded with feet back into aboard, holding tight to prevent a wild swing. Then it damp boots, salt-clammy raingear over our clothes. was teamwork on the run, to prepare the line and And so for seven days, until our tanks were filled.
    [Show full text]
  • Midwater Trawls and Their Operation
    Midwater Trawls and their Operation V. Vijayan Central Institute of Fisheries Technology P.O. Matsyapuri, Cochin-682 029 India, according to FAO of UN (1998) is overall third and fifth in marine fish production among the world’s top ten producers of fish. Working group for revalidating potential fishery resources in the Indian EEZ constituted by the Dept. of Animal Husbandry, Min. of Agriculture, Govt. of India in its report released in Oct. 2000 came out with details which call for strict monitoring of resources especially region-wise and species-wise to enable rendering advice on management measures to be adopted and that the time has come to stop open access and evolve regulatory mechanisms for judicious utilization of resources’. The total potential yield of the marine fishery resources of Indian EEZ was revalidated to 39,34,417 tonnes consisting of • 20,17,072 tonnes of demersal resources; • 16,73,545 tonnes of pelagic resources; and • 2,43,800 tonnes of oceanic resources. One of the disturbing trend observed was the substantial reduction of some important conventional resources totaling 6.26 lakh tonnes. Elasmobranchs : 97,000 t Cat fish : 72,000 t Clupeids : 1,31,000 t Ribbonfish : 1,17,000 t Carangids : 2,09,000 t Overfishing has been identified as the reason for this reduction in quantity of resources and effective control of fishing capacity ad fleet control are absolutely essential as preventive measures. Gear restrictions have an important role to play in making optimal use of a stock or a resource. Effective use of pelagic or semipelagic trawl, which are target specific, can prevent irresponsible exploitation and subsequent reduction of fish stocks to biologically and ecologically harmful levels.
    [Show full text]
  • Technical Report on the Midwater Pair Trawl Experiment to Harvest Offshore Fl Ying Squid British Columbia 1995
    TECHNICAL REPORT ON THE MIDWATER PAIR TRAWL EXPERIMENT TO HARVEST OFFSHORE FL YING SQUID BRITISH COLUMBIA 1995 EXECUTIVE SUMMARY AND REPORT Prepared by: Captain David Tait Scantec Limited 84 Thornhill Drive Dartmouth, Nova Scotia Canada 838 1 S3 Prepared for: Department of Fisheries and Oceans Responsible Fishing Operations Program Planning & Coordination Fisheries Management 200 Kent Street Station 1412 Ottawa, Ontario Canada K1A OE6 and Deep Sea Trawlers Association of 8 .C. Unit 2, 11771 Horseshoe Way Richmond, 8.C. Canada V7 A 4V4 EXECUTIVE SUMMARY The project was aimed at diversifying the B.C. trawler fleet sector from fishing pressure stocks into designated underdeveloped species, thereby taking the stress off traditional species. Since the ban on drift net fishing techniques in the Pacific, total harvesting of Offshore Flying Squid (Ommastrephes bartrami) has been at a standstill. The Department of Fisheries and Oceans, in cooperation with the Deep Sea Trawlers Association of British Columbia, initiated and funded a project to survey the possibilities of harvesting this species using Pair Midwater Trawl technology. The objective was to evaluate Pair Midwater Trawling as an alternative technique to harvest flying squid. Towing on the surface, and at different levels in the water column, and introducing diel variations into the fishing pattern, were examples of the experiments made during the project. Surface temperatures were monitored and recorded, and fishing was conducted in different isotherms. The scope of the search was spread over a large sea area, and as far West as Latitude 45 Degrees North, Longitude 146 Degrees West. The vessels steamed approximately 3,000 miles, and actual fishing time was approximately 60 hours.
    [Show full text]
  • Insert Project Title
    PRE-SURVEY FISHERY ASSESSMENT PORCUPINE BASIN, SOUTHWEST COAST OF IRELAND ENI IRELAND BV DUNQUIN SOUTH SURVEY 2019 Carried out by: Eimear Stafford ________________________ Sinbad Offshore Support Limited Church Road,Killybegs Co. Donegal Dated: 28th March, 2019 TABLE OF CONTENTS 1 INTRODUCTION ................................................................................................................ 3 1.1 PROPOSED GEOPHYSICAL AND GEOTECHNICAL SURVEY ......................................................................... 3 1.2 SURVEY LOCATION .......................................................................................................................... 3 1.3 KEY GEOGRAPHICAL CHARACTERISTICS ............................................................................................... 3 2 FISHERIES ......................................................................................................................... 6 2.1 FISHERIES MANAGEMENT ................................................................................................................ 6 2.2 COMMERCIAL FISHERIES OVERVIEW AND CATCH STATISTICS .................................................................. 7 2.2.1 Demersal Fisheries ............................................................................................................ 8 2.2.2 Demersal Catch Statistics ................................................................................................ 10 2.2.3 Pelagic Fisheries .............................................................................................................
    [Show full text]
  • Report Shifting Gears Addressing the Collateral Impacts of Fishing Methods in US Waters
    SHIFTING GEARS Addressing the Collateral Impacts of Fishing Methods in U.S. Waters Lance E. Morgan Ratana Chuenpagdee PEW SCIENCE SERIES PEW SCIENCE SERIES Public debate and policy decisions tives: first, to communicate the regarding management of natural results of sound scientific research resources should be guided by good science. on problems that are or will soon be at the Too often, they are not. In some cases, the forefront of environmental decision making problem is a lack of data. In others, it is the and debate; and second, to do so in a way tendency to sacrifice the dictates of good sci- that is readily comprehensible to policymak- ence to the exigencies of politics. In many ers, resource managers, the media and the instances, however, the problem is not the public. absence of scientific information or an The intent of the series is not to simplify unwillingness to pay attention to it. Rather, the scientific endeavor. Rather, it is to make it is that the available scientific data is fre- the fruits of that endeavor more accessible to quently unintelligible to decision makers as those people and institutions charged with well as those who shape public opinion. making decisions that will affect the future The goal of this series of publications health and, in some cases, very survival of is to bridge the gap that so often exists those natural systems upon which human between scientists working to illuminate the society depends. causes and consequences of specific environ- mental problems, and those individuals who Joshua Reichert are faced with making decisions about how Director to address these problems.
    [Show full text]