Purse seine and longline fishing gear and vessel efficiency
May 11th, 2010 molitva leyli

An examination of vessel, gear and operational details useful for fishery-specific effort standardization, including FAD-related gear and fishing strategies

By ; David G. Itano, Pelagic Fisheries Research Program, Honolulu, Hawaii – ESTHER (Efficiency of the Tuna Purse Seiners and Effective Effort).

pelagic_longline

The European Union funded 3 research project ESTHER (Efficiency of the Tuna Purse Seiners and Effective Effort) examined vessel and gear attributes of the EU purse seine fleets and conducted analyses and modeling to gauge the impact of various factors to fishing efficiency (Gaertner and Pallares 2002).. These factors were considered key technical improvements adopted by EU purse seiners that significantly increased vessel efficiency:

  1. opening style roller purse rings;
  2. use of drifting, instrumented FADs;
  3. use of auxiliary FAD support and supply vessels;
  4. installation and use of bird radar;
  5. increasing familiarity with and more powerful sonar;
  6. increased power of purse winch and power block;
  7. increased vessel speed when competing in areas of high school density.

purse-seine-technic

The ESTHER program also noted the following issues that tend to complicate the measurement of effective effort or generally confound these efforts. These points may not appear novel but bear listing here as a reminder of the difficulties involved.

  1. The collection of technical data from vessels was made difficult due to limited cooperation from industry and very few boats voluntarily accepted scientific observers;
  2. technological innovations occurred continuously making it difficult to tease out discrete influences;
  3. the need to examine factors on a fleet by fleet basis. For example the age of vessel may be a negative factor for one fleet but be positive or of no consequence for another that regularly improves and upgrades vessels;
  4. the fact that many innovations in gear have a positive combined effect, making the inluence of single pieces of equipment difficult to discern and measure;
  5. that some items may replace others, so the loss of one item may be compensated or improved by another, i.e. helicopters replaced by bird radar;
  6. that personal preferences of the captain or navigator may have more influence on gear use and efficiency, i.e. having a bird radar and a helicopter may not double efficiency as only one maybe favored by the captain, however having both may increase overall efficiency in case one is disabled.

Longline vessels and gear

Beverly (2001, 2002) reported on the status and improvements to tuna longline technology. The following technical improvements or recent developments in regional longline fisheries were considered especially significant:

  1. improved monofilament longline reels (more power, higher capacity, less wear, lighter);
  2. electric fishing lights to replace chemical light sticks;
  3. use of temperature/depth recorders during sets;
  4. electronic chart plotting software integrated with bridge electronics;
  5. use of remote sensing data (SST, altimetry, chlorophyll);
  6. rapid expansion of longline effort by vessels from Peoples Republic of China;
  7. development of onboard processing of tuna to loins; combination of freezing and chilling capability on the same vessel; diversification of markets.

Koyu Maru 3 longliner hauling tuna


Purse Seine Vessels and Gear

In review of papers on purse seine gear and technology, the author proposed that purse seine efficiency can be defined by an increasing ability to land a given quantity of tuna in less time, or an increased catch potential in a given time period (one year). This increasing efficiency consists of increasing actual fishing time, minimizing in port turnarounds, increasing the speed with which tuna can be caught, loaded and frozen onboard and decreasing overhead costs. It was proposed that purse seine efficiency can be achieved by:

1. Adequate fishing power large deep net designed for fast pursing

  1. full complement of electronics for tuna school assessment (high and low frequency sonar, scientific grade echo sounders, remote telesounder in skiff)
  2. adequate hydraulic power to quickly purse large net closed

2. Minimizing time to load catch

  1. rapid net hauling, stacking and sacking up with large capacity hydraulics
  2. installation of rubberized rail roller to speed sacking up process
  3. use of “Spanish style” sacking and brailing of catch to holds (see Itano 2003)

3. Advances in refrigeration and processing

  1. ability to load and preserve very large sets and maintain quality in warm waters, i.e. improved freezing capacity per hour

4. Increase of actual fishing effort during trips via:

  1. use of remotely monitored drifting FADs to maximize fishing time with sophisticated radio buoy technology (see Itano 2003)
  2. use of supply or tender vessels for FAD deployments and retrieval to monitor FAD aggregations and protect productive FADs from poaching (see Arrizabalanga et al. 2001)
  3. use of bird radar to remotely assess unassociated schools and plan movements between schools (see Gaertner, D., and P. Pallares 2002)

5. Decrease of down-time between fishing trips

  1. modifying fish well unloading system to “float” the catch to conveyor belts on the wet deck (see Itano 2003)
  2. design vessel layout to allow simultaneous unloading from several different fish wells
  3. configure fish wells and refrigeration system to allow sorting of catch at sea to market categories to speed unloading or transhipment
  4. transhipment of catch at sea or in port close to fishing grounds

6. Adoption of innovative new technology and methods that enhance any of these main areas of increased efficiency

Posted in FISHING boat ship vessel, FISHING GEAR, LONGLINE FISHING, PURSE SEINE FISHING Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
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