TECHNOLOGIES CURRENTLY USED DIRECTLY OR INDIRECTLY IN

FISHERIES MANAGEMENT

Ian Hampton

Cape Town

South Africa

 

 

  1. Surveys of stock size (absolute or relative)
  1. Stock definition
  1. Analysis methods

NEW TECHNOLOGIES/METHODS

ACOUSTIC SURVEYS

Problem

Abs/Rel

New or improved technologies/methods

Target Strength

A (+R?)

Extend density range of in situ method

    • Improved single target recognition (multi-freq. split-beam, tracking)
    • Shorten range to target (towed transducers, AUV)
    • Integration + high-resolution counter

Theoretical studies-improved models

Improved ex situ experiments?

Calibration

A

Improve beam mapping - beam factor

Effective sampling volume (echo-counting)

A (+R?)

Better-defined beams - beam- forming

Inadequate resolution

(echo-counting)

A (+R?)

Better-defined beams - beam- forming

Target identification

A + R

Multiple net samplers

DFA

Neural network analysis

Frequency-dependence of back-scatter

Near-surface targets (avoidance and surface blind zone)

A + R

Multi-beam sonar (vertical +horizontal?) + distance-sampling analysis

AUV

Near-bottom targets

(dead-zone)

A + R

Towed transducers

AUV

Theoretical corrections

Sampling error

A + R

Improve survey designs

    • effort allocation according to expected spatial structure
    • adaptive sampling

Trawl selectivity (target identification)

A + R

Target identification by acoustics

Observation of fish reaction to trawl (trawl sonars, video cameras etc.)

Aeration

A + R

Keel-mountings for transducers

Towed transducers, AUV

Vessel motion

A + R

Towed transducers, AUV

Transducer stabilisation

Noise limitations

A + R

Reduce vessel noise (e.g. diesel/electric propulsion)

Towed transducers, AUV

Data analysis

A + R

Improve estimators of mean and sampling variance based on spatial modelling

Estimation of overall error

A + R

Error modelling ( e.g. Monte Carlo simulations), based on best estimate of nature and magnitude of individual sources of error

 

 

TRAWL SURVEYS

Problem

Abs/Rel

New or improved technologies/methods

Catchability coefficient

(avoidance, herding, escapement)

A (+R?)

Observation of fish reaction to trawl (trawl sonars, video cameras etc.)

Gear comparison experiments

Fish above net

A (+R?)

Assess acoustically (trawl-mounted or hull-mounted transducers)

Trawl performance

A (+R?)

Better use of net-monitoring equipment

Untrawlable grounds

A (+R?)

Use heavier gear

More precise positioning of trawls in

relation to bottom characteristics and features (make better use of sea-bed characterisation and trawl positioning systems)

Re-survey acoustically when/if fish off bottom

Sample by other fishing methods ( e.g. long-line)

Sampling error

A + R

Improve survey designs

    • Trawl allocation according to expected spatial structure
    • Adaptive sampling

Data analysis

A + R

Improve estimators of mean and sampling variance based on spatial modeling

Estimation of overall error

A + R

Error modeling (e.g. through Monte Carlo simulations), based on best estimate of nature and magnitude of individual sources of error

 

 

ICHTHYOPLANKTON SURVEYS

 

Problem

Abs/Rel.

New technologies/methods

Sampling variance

A +R

CUFES - use adaptively

Spawning fraction (egg production methods)

A + R

New histological methods ?

Egg counting

A + R

Optical plankton counters

Egg mortality

A + R

Increase sample size - CUFES

Net selectivity (larval surveys)

A (+R?)

Multi -samplers

Compare with size distribution from multi-frequency acoustic methods

Survey design, data

analysis and error

quantification

A + R

As for acoustic and trawl surveys

AERIAL SURVEYS

 

Problem

Abs/Rel

New or improved technologies/methods

Low detectability

A + R

LIDAR

Image-intensification, image enhancement and object- recognition systems

Identification

A + R

Combine with acoustic ground-truthing (cf. acoustic target identification methods)

Automated object-recognition systems

Target quantification

A + R

Automated optical image-recognition and processing systems

Safety

 

Unmanned platforms?

Survey design, data

analysis and error

quantification

A + R

As for acoustic and trawl surveys

 

 

SHIPBOARD SIGHTINGS SURVEYS

 

Problem

Abs/Rel

New or improved technologies/methods

Detectability

A + R

Distance-sampling analytical methods

Double-platform/observer methods (e.g. sightings + multi-beam sonar)

Biomass of schools

A (+R?)

Assess acoustically ( sonar + echo-sounder) - research and commercial vessels equipped with multi-beam sonar

Survey design, data

analysis and error

quantification

A + R

As for acoustic and trawl surveys

 

This page is maintained and was last updated 15-Nov-00 by Pip Sumsion (sumsionp@dfo-mpo.gc.ca).