New Zealand’s native freshwater fish are becoming increasingly threatened

New Zealand's native freshwater fish are becoming increasingly threatened
The conservation status of New Zealand freshwater fish was assessed in June 2013 using theNew Zealand Threat Classification System. The threat ranking lists are often misconstrued as being ‘owned' by the Department of Conservation. However, although the listing exercise for all New Zealand taxa is the responsibility of the Department of Conservation, expert panels are made up of individuals from a broad range of organisations and should be referred to as New Zealand's threat classification lists.

The freshwater fish expert panel reviewed the status of 77 species, of which 54 are native residents. There has been a 9 percent increase in the number of species that are ranked as either ‘Threatened' or ‘At Risk' from 65 percent in 2009 to 74 percent in 2013. This increase is cause for concern because along with freshwater invertebrates and plants, our native freshwater fish are indicators of the health of our streams, wetlands and lakes. We rely on clean freshwater for a variety of reasons, all of which contribute to our wellbeing as individuals and as a society.

The reasons documented by the expert panel for the decline in distribution and abundance of our native freshwater fish were a combination of the following threats and pressures:

loss and/or degradation of spawning and adult habitat due to land use intensification
competition and/or predation by introduced species
declining water quality and water abstraction
impediments to upstream and downstream migration
or fishing pressure.

For some of our fish species, if the pressures and threats continue to impact on their habitat and population size, the next category they may be assigned to in the classification system is ‘Extinct'. For example, one species classified as ‘Nationally Critical', the Teviot flathead galaxias (Galaxias"Teviot") is found in only 0.5 ha of habitat in the Teviot River. This doesn't paint a particularly good picture for our freshwater fish; however although it will take a lot of hard work, co-operation and compromise from many different groups we do have the know-how to ensure a more positive story in the future.

Our freshwater fish, while not quite as famous or charismatic as DOCs spokes bird Sirocco (yet!) and better known for how they taste in a fritter, do have a small but growing group of supporters. These supporters were initially those of us that study freshwater fish and work as ecologists or conservations, but now extend to landowners, school children and community groups. This growing support is thanks to the awareness raised by many different organisations. Within the Department we have had a group of dedicated Rangers working mainly in Otago to increase our understanding of some of our most threatened freshwater fish species; at the same time they have increased awareness of these species and worked with landowners to protect some populations.

Recently, my colleagues and I visited a farm in Northland that is part of the Hikurangi Swamp Fonterra DOC partnership. The landowner at this site was more than willing to fence and plant his stream, go beyond what was required and was interested in what species were in the stream. He had a lot of questions about where, how and why to fence and plant, and what changes he could expect to see if he did what we suggested. This experience made us all think more about the time, effort and knowledge required to make changes, even in a small stream where there was willingness from all parties.

For those of us that have knowledge of freshwater fish and their habitat requirements, our challenge is to work with landowners to ensure we communicate this information in a way that they can use in practice. Perhaps, even more importantly we also need to continue to raise awareness of freshwater fish, their fascinating life-cycles, intrinsic value and contribution to the economy as indicators of ecosystem health. Yes, we do need willing people to work with, but to get people to change we first need them to care.

Source: SCI Blogs

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Taxonomy

• Habitat
• Aquatic Environment
• Animal Health