These pages are still under construction |
| Indicator | Attribute | Purpose | If restricted to taxa, list which ones | Ecosystem applicability | Identified capability | Biological classification level | Response variable | Drivers | Robustness |
|---|---|---|---|---|---|---|---|---|---|
| Rate of catch of species at risk, Potential Biological Removal (PBR) rates | Efficacy of bycatch reduction mitigation measures, Discard availability or depletion, Community structure, Trophic structure, Population structure | Fisheries, Marine mammals, Seabirds, Penguins, Marine turtles, Sea snakes | Should be applicable to all marine ecosystems | Aspirational | Population, Community, Ecosystem | Species-based | Trophodynamic, Anthropogenic | Low |
| Indicator examples | Current status and trends | Management objective/direction | Stakeholder/Public acceptability |
|---|---|---|---|
| Examples of how the indicator is used. | Pick one of the following:
| Pick one of the following:
| Pick one of the following:
|
| 1999 ‘Threat Abatement Plan for the incidental catch (or by-catch) of seabirds during oceanic longline fishing operations’ for Australia’s AFZ | |||
| In New Zealand, the planned approach for measuring mortality of albatross species in longline operations is to record the number of incidental seabird mortalities rather than catch rate per hooks or tows | |||
The following is from Fulton et al 2004a -
Whilst it is essential to record incidental catch records from fisheries, so that mortality of non-target species can be estimated, it is especially important to understand the levels of mortality for species at risk (e.g. species of marine mammals, seabirds, marine turtles, chondrichthyans and sea snakes). However, mortality alone cannot be a robust indicator unless it can be interpreted in the context of a sound scientific research data available on population dynamics, ecology and reference areas for the species of interest.
Methods of mitigating bycatch of non-target species through changes in gear technology, deployment and changes to fishing operations have become one important focus of fishery management and the reduction of ecological impacts. One of the current trends in managing catches of non-target species at risk (e.g. seabirds) is to set catch limits, either as total catch or as catch per unit effort of fishing, e.g. numbers of seabirds caught per hook or per tow. ... This catch rate of seabirds is essentially an indicator for the efficacy of bycatch mitigation devices and strategies imposed on a fishery to reduce the impact on the populations of species at risk. However, there is debate about the usefulness of this indicator, because if fishing effort increases and is not reliably recorded the catch relative to effort can artificially show a decline in incidental catch (and therefore give a false impression that mitigation is working), or worse still, will dilute the power of scientists and managers to detect accurate catch levels. Alternatively, a decline in the population of seabirds could also lead to a decline in the indicator, as there are less seabirds to capture in the first place. ... One solution may be to use reference points. Reference points for viable seabird populations, would need to be based on historical data where available, or empirical data on natural mortality and adult survivorship rates, but obtaining these important data will require dedicated research efforts.
Efficacy of bycatch reduction mitigation measures, Discard availability or depletion, Community structure, Trophic structure, Population structure
Fisheries, marine mammals, seabirds, penguins, marine turtles, sea snakes
The following is from Fulton et al 2004a -
The following is from Fulton et al 2004a -
Should be applicable to all marine ecosystems.
Is there any additional information that would be of interest in regards to the identified capability?
Otherwise can leave this section blank and just fill in the table instead.
Is there any additional information that would be of interest in regards to the biological classification?
Otherwise can leave this section blank and just fill in the table instead.
Is there any additional information that would be of interest in regards to the response variable?
Otherwise can leave this section blank and just fill in the table instead.
Is there any additional information that would be of interest in regards to ecological drivers?
If not can leave this section blank and just fill in the table instead.
The following is from Fulton et al 2004a -
Relative catch rate: Low, because the success of this bycatch rate as an indicator of the efficacy of bycatch mitigation measures is dependent on an effective observer program being implemented and maintained to monitor catches, or on fishers returning all dead seabirds; fishers accurately reporting on bycatch levels; and no increase in effort. Ideally there should be no substantial decrease in the bird population either. The limitations of this indicator include the reliability of catch data supplied by fishers and the practicality of placing observers on fishing boats for the number of years required to collect regular and statistically robust, consistent data. As a result, data are therefore potentially unreliable and invalidated. This indicator could be improved if catch rates for each species rather than aggregated seabird catch data could be recorded.
Total catch: Low because data needs to be species specific, especially for threatened species, and needs to be underpinned by scientific studies of population dynamics (e.g. adult survival (seabirds), pupping rates (pinnipeds), juvenile recruitment (shark species) and ecology (e.g. differential foraging ranges for albatross species, or movement patterns for many shark species). Where this information exists, the indicator will become more robust. Note however, that care also needs to be taken when interpreting the total bycatch against a set threshold limit, especially if the population structure is unknown. For example, Gales and Fletcher (1999) found in a study of the New Zealand sea lion, that not all breeding stocks of the south island population were subject to bycatch, and that if only an aggregate population is being monitored, depletion of the harvested stocks or population could occur without being detected. Thus, it is important to identify which stocks are being subjected to bycatch and obtain data on total bycatch of each stock.
The following is from Fulton et al 2004a -
In Australia, under the 1999 ‘Threat Abatement Plan for the incidental catch (or by-catch) of seabirds during oceanic longline fishing operations’ for Australia’s AFZ (Environment Australia 1999), an aggregated seabird bycatch threshold rate has been set at 0.05/1000 hooks at the 1997 longline effort limits. The catch rate has been chosen to ‘reflect the ability of currently available mitigation measures to reduce seabird by-catch’ (Environment Australia 1999) and if successful this catch rate should see a reduction in seabird mortality of up to 90% in the AFZ.
In New Zealand, the planned approach for measuring mortality of albatross species in longline operations is to record the number of incidental seabird mortalities rather than catch rate per hooks or tows, because the interest is detecting the reduction of the total number of seabirds caught through fishing operations over time (New Zealand Ministry of Fisheries and the Department of Conservation 2000). However, while this avoids the issue of the effects of effort on the indicator it will not guard against declines in population size impacting upon the indicator.
Some of the issues mentioned above for seabirds have already been addressed for marine mammals. Reference points for marine mammals, in the form of mortality limits have been determined for all 153 USA stocks using Potential Biological Removal (PBR) rates. The PBR is the maximum number of animals, not including natural mortalities, which may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population. Mathematically, PBR is defined as:
where Nmin is the minimum population estimate of the stock, ½ R max is one-half the maximum theoretical or estimated net productivity rate of the stock at a small population size, and Fr is a recovery factor between 0.1 and 1.(Wade 1998). An example of the use of PBR in a fishery can be found in New Zealand, where threshold limits for the bycatch of the endemic New Zealand sea lion Phocarctos hookeri, (one of the world’s rarest pinnipeds) in the arrow squid fishery have been set at 63 individuals of any age or sex class or 32 females per annum. These numbers were based on 1993 USA/NMFS fisheries guidelines, which state that a population must not fall below its maximum net productivity level. Where that level for marine mammals is thought to be between 50% and 85% carrying capacity (Wade 1998).
define a standard set of management objectives?? ie from Indiseas
has it been used in a management strategy? if so how?
relationship to management strategies/ objectives
Acceptability with stakeholders
Hyperlinks to organisations, databases, webportals, and ID books, that are associated with this indicator, if appropriate.
Fulton, E.A., Smith, A.D.M., Webb, H., and Slater, J. (2004a) Ecological indicators for the impacts of fishing on non-target species, communities and ecosystems: Review of potential indicators. AFMA Final Research Report, report Number R99/1546.
References that Fulton et al uses for this indicator:
Environemnt Australia (1999) ----need to find reference---
Gales, N. J., and D. J. Fletcher. 1999. Abundance, distribution and status of the New Zealand, sea lion, Phocarctos hookeri. Wildlife Research 26: pp 35-52.
New Zealand. Ministry of Fisheries, and New Zealand. Department of Conservation. 2000. "Seabird limits." Seabird interaction with fisheries in the New Zealand exclusive economic zone: a review and national plan of action, New Zealand. Ministry of Fisheries, and New Zealand. Department of Conservation.
Wade, P. R. 1998. Calculating limits to the allowable human-caused mortality of cetaceans and pinnipeds. Marine Mammal Science 14, no. 1: pp 1-37.
Ward, T., E. Butler, and B. Hill. 1998. Environmental indicators for national state of the environment reporting: estuaries and the sea. 84 p . Australia: State of the Environment - (Environmental Indicator Reports). Canberra, ACT: Environment Australia.
Fulton, E.A., Fuller,M., Smith, A.D.M., and Punt, A. (2004) Ecological indicators of the ecosystem effects of fishing: Final report. AFMA Final Research Report, report Number R99/1546.
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