41_KAH_09

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41_KAH_09 .pdf

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41_KAH_09 .pdf (273.9 kb)

Abstract
KAH 1
An assessment was undertaken for KAH 1 in 2007. In the assessment for KAH 1 there was uncertainty in some important model inputs (e.g., recreational catch history and abundance indices) and some influential biological parameters could not be estimated within the model (e.g., natural mortality and the spawner recruitment relationship).

The approach taken to represent uncertainty was to determine the four main factors for which uncertainty was likely to have an impact on key model outputs (referred to as the ‘axes of uncertainty’) and then to select a limited number of plausible options across each axis. Model runs were then undertaken for all possible combinations of options across each axis – this set of options was referred to as the ‘grid’. Overall, the grid comprised 36 model runs which in totality were thought to be a realistic reflection of the extent of uncertainty in the KAH 1 assessment.

Based on the scenarios examined, it is Likely that current spawning biomass is above BMSY, but it is uncertain how far above.

Current assumed removals are lower than almost all estimates of deterministic MSY. Combining this with the result that most estimates of current biomass are well above BMSY it is unlikely that the stock will decline below BMSY at current assumed catch levels, given the model recruitment assumptions.

The current TAC for KAH 1 is 3315 t with a TACC and allowances outlined in Table 1. The estimates of deterministic MSY depend on model assumptions, in particular the assumed natural mortality and time series of non-commercial catches. When non-commercial harvests are assumed to have been 800 t per year, median MSY estimates from grid strata range from 2130 to 4007 t. When non-commercial harvests are assumed to have been 1865 t per year, median MSY estimates from grid strata range from 3042 to 5564 t.

Within the range of non-commercial catches investigated, estimates of stock status are relatively insensitive to the absolute level of the non-commercial catch, provided that these catches are assumed to be constant over the model period.

Deterministic projections assuming M=0.18 and including all abundance indices were undertaken in 2008 based on the 2007 assessment and the current TACC and assumed non-commercial removals. These indicated that biomass was predicted to increase over the next five years for both steepness and non-commercial catch scenarios.

All other KAH regions
No accepted assessment is available that covers these regions. It is not known if the current catches, allowances or TACCs are sustainable. The status of KAH 2, 3 and 8 relative to BMSY is unknown.

Document date
Sunday, 31 May 2009

Document type
V 1.3

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Adobe PDF

File size
273.9 kb

Reference number
2009

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M:\SCIPOL\Working Groups 2009\Plenary 2009\FINAL\MFish 2009 May Plenary\May 2009 - PDF\41_KAH_09 .pdf

Uploaded date
Thursday, 11 June 2009

Search tags

Species: KAH;
Stock: KAH1; KAH10; KAH2; KAH3; KAH4; KAH8;

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