Description: <DIV STYLE="text-align:Left;font-size:12pt"><P><SPAN>The distribution of commercial trawl catch is estimated for trawl fishing events reported in statutory catch and effort returns for the period 1 October 2007 to 30 September 2019.</SPAN></P><P><SPAN /></P><P><SPAN>The location of trawl fishing events is reported by start or start and end coordinates precise to 1 nautical mile.</SPAN></P><P><SPAN /></P><P><SPAN>The total catch of all species from each fishing event is spread uniformly over a polygon of space estimated to be occupied by that fishing.</SPAN></P><P><SPAN /></P><P><SPAN>Trawl fishing polygons are derived from the length and width of the door-spread for the duration of the tow.</SPAN></P><P><SPAN>The path of each tow is taken as a straight line between start and end coordinates where these are reported, or between start and estimated end coordinates. Where not required to report end coordinates, (as is the case for most inshore trawling) tow end points are derived using the direction of the next tow start position or the direction of the landing point for the last tow of the day.</SPAN></P><P><SPAN /></P><P><SPAN>Catch intensity (kg/ha) is mapped to a square kilometre grid for all fishing events and summed. The data is aggregated into grid squares of between 1 and 2500 km2 as required to give 12-year annual averages of data from at least three permit holders. Catch per unit area values are classified into ten intensity classes.</SPAN></P><P><SPAN /></P><P><SPAN>MPI has high confidence in the data on catch quantities used to create this data but the spatial distributions of those catches are only approximate and should be used with caution especially at large map scales (maps of small spatial extent). Nevertheless, the aggregation of a large number of fishing events tends to provide consistent patterns that have passed scrutiny when tested with groups of fishers.</SPAN></P><P><SPAN /></P><P><SPAN>Grid squares with less than 3 permit holders present have removed in order to confidentialise the data. </SPAN></P><P><SPAN /></P><P><SPAN>The data has been approved for public release by the data owner, Team Manager, Fisheries Data Management as permit holders and catch values have been aggregated as part of the confidentialisation process and to align with MPI's commitment to promote open data.</SPAN></P><P><SPAN>Please contact the data owner for any questions in relation to the release of this data ([email protected]). </SPAN></P><P><SPAN /></P><P><SPAN>The data custodian for this data is the Spatial Intelligence team ([email protected]). </SPAN></P><P><SPAN /></P><P><SPAN>The data is also displayed on the MPI website as the trawl fishing intensity map.</SPAN></P></DIV>
Service Item Id: 6259f93e247245f8a401d5df7bc2c807
Copyright Text: Ministry for Primary Industries (MPI) - Manatū Ahu Matua