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4. Overview
The programme of work was successful in regard to the two primary aims set at the commencement of 2001 ie increased information on twaite shad and extension of baseline on sea lamprey spawning. The notable successes of the survey programme include:
- Database on allis shad commenced
- Database on river lamprey commenced, including identification of a suitable sampling technique for migrating adult fish.
- Confirmation of existence of an autumn run of river lamprey into some Irish rivers.
- Confirmed value of direct observation for enumeration of sea lamprey spawning effort
- Widespread distribution of smelt, of differing age classes, identified in both the Suir and Barrow estuaries
The study findings indicated a number of disappointing aspects including:
- Failure to collect juvenile twaite shad and juvenile Killarney shad despite extensive effort. This may be a consequence of low numbers or may relate to the nature of the sampling method and the locations sampled
- Shortcomings in sea lamprey spawning site counts, with a considerable degree of spawning occurring simultaneously in a number of channels. This confines sampling to a small number of channels, only. The variations in timing of spawning may also lead to counting being done ‘early’ or ‘late’ in any season. The experience in 2001 suggested that the spawning sites on the Suir, clearly identifiable in the initial survey in June, were much less obvious in July.
- The identification of shortcomings, as well as successes, is important in the development of a programme of investigations for 2002. It is clear from the findings in 2001 that much remains to be learned in regard to ecology, distribution and status of the conservation species in Ireland and further investigations are required
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