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Database Title

7.29 Ministry of Fisheries research trawl database ("Trawl")

 
Keywords
Type1.

Type 11.		 New Zealand EEZ; marine; oceans; fisheries; biomass; catch; occurrence; distribution; age; size; trawl. 
Abstract

Contains both inshore and deepwater research trawl survey data from both research and chartered vessels. Information collected includes stratum, station, catch, and biological data. The database contains all trawl surveys from 1988 and many from pre-1988.

While trawl survey data constitutes the bulk of the data held in trawl, they do not represent all the data. The database design allows for any data to be stored from a trip that has one or more stations that deploy some sort of gear.

Species in the trawl database include orange roughy, hoki, oreos, baracouta, spiny dogfish, arrow squid, hake, southern blue whiting, ling, warehou, red cod, snapper, and many others. Prior to 1979 less than a hundred stations per year were sampled and snapper was the main species surveyed. From 1979 onwards numerous species were surveyed and over 600 stations per year were sampled. 

Geographical Coverage New Zealand EEZ excluding Kermadec Islands and areas below 1400 m.
Dataset start date. 1960
Dataset end date. Current
Status/currency. In progress
Update frequency. Annual
Maintenance. NIWA

 

Technical Evaluation

  
Parameters- what is measured For each trawl: surface temperature, weather, water clarity; weight of each fish species.
For a subset of fish species: length, individual weights, sex, otoliths; and sometimes stomach contents and gonad state.
Parameters- what is calculated For each fish species:
  • Biomass
  • % catch
  • % occurrence
  • Length frequency distribution
  • Age frequency distribution
  • Total fish biomass in area
  • Geographical distribution of catch rates
Methods used to measure parameters Collected by research trawls. Over the time of the database approximately 20 vessels have been used. Different surveys may have different gear/ methods and so data between surveys is not necessarily comparable. A survey series is often annual to begin with and then every 2-3 years. There are approximately 50-70 trawls /survey.
Scale of use. Variable
Number of records At 12 May 1997: 22,619 tows with 335,469 occurrences of 634 species and species groups.
GIS compatibility. Not to date.
It is possible as latitude and longitude data is collected.
Available formats for users. Electronic relational database; requests are usually responded to with a flat file (Excel, ASCII).
Numerous reports that analyse the data
Access constraints. By request to the Ministry of Fisheries. There is no cost for the data although there is a NIWA charge to extract data.
Measurement Accuracy To be completed by database manager.
Completeness of dataset To be completed by database manager.
Positional accuracy To be completed by database manager.
Database steward Ministry of Fisheries
Steward contact person. Kim Duckworth (Research Data Manager)
Database custodian NIWA
Database custodian contact person Don Robertson
Database custodian Contact
Address

Phone
Fax
Email		 PO Box 14 901
Kilbirnie
Wellington
+ 64 4 386 0519
+ 64 386 0572
d.robertson@niwa.cri.nz
References Mackay, K.A. 1998. Database documentation: trawl. NIWA Internal Report No 16
Anderson, O.F; Bagley, N.W.; Hurst, R.J.; Francis, M.P.; Clark, M.R.; McMillan, P.J. 1998. Atlas of New Zealand fish and squid distributions from research bottom trawls. NIWA Technical Report 42. 303p
Bagley, N.W.; Anderson, O.F.; Hurst, R.J.; Francis, M.P.; Taylor, P.R.; Clark. M.R.; Paul, L.J. 2000. Atlas of New Zealand fish and squid distributions from mid water trawls, tuna long line sets, and aerial sightings. NIWA Technical Report 72. 171p.
Date metadata record prepared. June 2000
Author of metadata record. Victoria Froude

 

Management Evaluation

  
Original purpose. To improve fisheries management through single region surveys and time series biomass indices.
Relationships with classification systems. N/A
Relationships with other databases Information from this database is used with other fisheries databases and physical databases to address various management and research questions.
Known relationships with proposed EPIP indicators. May contribute to fisheries indicators.
Database uses? Most of the data is used for single fish species analyses. FORST has funded NIWA research into fish communities to identify fish assemblages that regularly occur together. This will include papers on :presence/absence within the whole of the EEZ (where differences in gear or method limits the extent of analysis) and regional studies using survey sets where the abundance and weight data can be used.
Public awareness of the database Medium - fishing industry
Database strengths.
  • There is a lot of data especially inshore. Key areas include Bay of Plenty-Hauraki Gulf, Western North Island, South Island West Coast and the Chatham Rise.
  • Some surveys series have run for a number of years (e.g. Hauraki Gulf since 1982). This provides time series consistent data.
Database limitations.
  • Data in different survey series may not be directly comparable depending on the questions being asked.
  • There is sparse coverage in Fiordland, Northern North Island ridges and for the Challenger Plateau.
  • Often the data can only be used to indicate fish species presence or absence because the abundance and weight data can not always be compared between surveys.
  • In recent years the number of surveys has decreased because industry (now the major funder) wants less research

 

What are the Current and Emerging Uses of the Database for:

  
Assisting with determining historic state/baseline. The database can be used to assess changes over time in locations where there is a regular series of data. Various research projects have modeled changes in the main commercial species. The fish distribution atlas (Anderson et al, 1998) starts to address changes in associated species.
Assisting with determining current state/baseline. The fish distribution atlas (Anderson et al, 1998) maps species distribution by location and overall depth. 
Assisting with modeling possible future outcomes. Models have been developed for the population trends and biomass of the main commercial species (e.g. orange roughy).
Risk assessment. The models are used to project likely future outcomes and risks under different senarios for the main commercial fish species. There is a project to identify the locations of juvenile fish. These are high risk sites for damage from bottom trawling.
Monitoring site selection and sample design. N/A
Aggregating and reporting data locally, regionally or nationally. This is possible.

For some species where there is insufficient information to predict population trends there is an agreement to allow the industry to increase its catch in exchange for an increase in the monitoring of those species. Examples include stargazer, red guarnard, and set net rig, and elephant fish.