Skip to Page Content
NOAA Fisheries
Geographic Information Systems
Aleutian Islands Redistribution of Catch

Aleutian Islands Redistribution of Catch

These maps were designed to supplement the tabular data analysis completed for both the Programmatic SEIS and the Essential Fish Habitat EIS in the Alaska groundfish fisheries.

The proposed spatial restrictions were created by analysts and committees of the North Pacific Fisheries Management Council. They were later analyzed by finding the amount of reduced fishing activity the closures would impose on the fishery using a technique called proportion allocation with net-effect 1.

An assumption was made when the proposed closures were created that the fleet would still likely catch most of their catch even though some of their historical fishing areas were now to be restricted or closed. The Red bars illustrate the restricted catch, the blue bars show the catch that can still be caught in that location, and the purple bars illustrate the catch after the redistribution. The purple bars simply represent the amount of restricted catch that has been redistributed into the same NMFS Reporting Area where that same species and gear type was used to catch the fish 2 . In the case of this map, Pacific cod is illustrated but in the data analysis, all fisheries were analyzed simultaneously.

The story does not end there as we needed to illustrate when the redistribution algorithm redistributed so much catch as to artificially change the dynamic of the fishery that is truly dominate in that area. This is coded into the green background state statistical areas. Note that the map on top illustrates the rate of P.cod fishery dominance in a state stat area before the redistribution and the map on bottom illustrates the rate of P.cod fishery dominance after the redistribution. It acts as an index of efficacy of the redistribution of catch algorithm.

1 Proportional allocation with net effect. The spatial common resolution of the fishery data is the Alaska State Statistical Area, generally about 30 miles high by 30 miles wide - small in comparison to the size of the Alaska fishery but large in comparison to the size of some proposed closures. In this instance we then used proportional allocation to determine what part of the state stat area was affected by the closure and used that as the multiplier. We further refined this proportional allocation by using just the fishable area (down to 1000 meter depth) of the state stat area.

Net Effect takes into consideration the historical closures and restrictions, such as the Steller Sea Lion Protection Measures that were in a effect but not represented by all the base data within the data.

2 In the final RIR/IRFA analysis, redistribution was used as a subjective tool; absolute restricted catch was used as the primary regulatory impact tool. The total restricted catch was multiplied by the relevant Exvessel or First wholesale value of the fish to find the potential economic jeopardy of the fishery.

NOAA logo Department of Commerce logo