Abstract:
Standard monitoring units for the recruitment of fishes (SMURFs) are tools that can be used to measure spatio-temporal trends in fish recruitment. However, little is known on how different habitat types and conditions within the same geographic region may affect SMURF catches. This thesis evaluated the influence of habitat type, microhabitat features and complexity on SMURF catches. Otolith microstructure was also conducted on individuals caught in SMURFs to compare the early life histories of recruits from different habitat types in northern New Zealand. Settlement in SMURFs was significantly greater in January 2010 for all the sampling sites. SMURF catches were dominated by the Blenniidae fishes Forsterygion lapillum and Forsterygion varium, with the east coast SMRUFs catching newly settled fish, whereas the west coast SMURFs were catching juveniles and adults. The Kaipara Harbour was found to have significantly lower species diversity and evenness than the east coast sites however, the Kaipara Harbour had greater overall catches. Otolith microstructure analysis of F. varium revealed no major differences spatially and temporally in larval characteristics (timing of when individuals were spawned, hatched and settled, pelagic larval duration, and early larval, late larval and juvenile growth rates). Multivariate analysis of microhabitat features adjacent to deployed SMURFs and a field experiment manipulating microhabitat complexity showed that adjacent microhabitat features and complexity did not heavily influence settlement in SMURFs. The total catches and species diversity garnered from SMURFs associated with different complexity treatments compared to experimental habitat complexity plots revealed that the species diversity from SMURFs were similar to the experimental plots. However, SMURFs caught significantly more fish than the experimental plots, especially the SMURFs associated with lower complexity treatments. The results of this thesis suggest that SMURFs sampled the plankton independently of the adjacent habitat, with habitat type and complexity having a stronger influence on post-settlement processes.