Evaluation of Ecological Effects of the North Sea
299
enormous data requirements and wide range of analytical issues arising within the
MSVPA model make it an inappropriate tool for annual assessments and day-to-day
management. On the other hand, the data generated for MSVPA can be used in
ecosystem models such as ECOPATH (Christensen and Pauly, 1992; Christensen,
1995) to examine a number of key ecosystem properties such as impacts and the flow
of biomass.
In this study, MSVPA, ECOPATH and other models were used to try to
obtain a clearer picture of the effects of different fisheries on ecosystem dynamics than
is currently available from the single species assessments alone. GIS distributional
resource data are used for individual species to ascertain species interactions. For
example, the industrial species comprise a significant part of the diet of cod, haddock,
whiting, mackerel and saithe. Thus, one potential explanation for the decline in human
consumption stocks over and above the effect of directed fisheries, is the alteration in
food availability caused by extraction of large amounts of fish biomass. One of the aims
of this chapter is to investigate whether the food demands of the human consumption
species are being met. We also need to know whether there would be enough food for
299
enormous data requirements and wide range of analytical issues arising within the
MSVPA model make it an inappropriate tool for annual assessments and day-to-day
management. On the other hand, the data generated for MSVPA can be used in
ecosystem models such as ECOPATH (Christensen and Pauly, 1992; Christensen,
1995) to examine a number of key ecosystem properties such as impacts and the flow
of biomass.
In this study, MSVPA, ECOPATH and other models were used to try to
obtain a clearer picture of the effects of different fisheries on ecosystem dynamics than
is currently available from the single species assessments alone. GIS distributional
resource data are used for individual species to ascertain species interactions. For
example, the industrial species comprise a significant part of the diet of cod, haddock,
whiting, mackerel and saithe. Thus, one potential explanation for the decline in human
consumption stocks over and above the effect of directed fisheries, is the alteration in
food availability caused by extraction of large amounts of fish biomass. One of the aims
of this chapter is to investigate whether the food demands of the human consumption
species are being met. We also need to know whether there would be enough food for