Towards a consistent approach for analyzing and reporting on the state of fish communities and trends within the SOSMART area

Transcription

1 Towards a consistent approach for analyzing and reporting on the state of fish communities and trends within the SOSMART area April 15, 2015 Introduction Representatives 1 of several Conservation Authorities (CA) in the SOSMART area (Central Lake Ontario Conservation Authority (CLOCA), Credit Valley Conservation Authority (CVC), Ganaraska Region Conservation Authority (GRCA), Halton Region Conservation Authority (HRCA), Lake Simcoe Region Conservation Authority (LSRCA), and Toronto & Region Conservation Authority (TRCA)) convened a meeting to discuss approaches to monitoring and reporting on the state of stream fish communities. The goal of the meeting was to: 1. Discuss the individual fisheries monitoring programs and determine similarities/differences to determine if the data could be analyzed on both a CA scale and larger SOSMART scale; 2. Explore options for developing a consistent and transparent methodology for measuring the state of and trends in fish assemblages; and, 3. Identify issues and solutions to ensure a more coordinated approach to monitoring fish assemblages is achieved within the SOSMART area and beyond. Background Each CA has been conducting fish surveys for a number of years (12-15 years) mostly using the Ontario Stream Assessment Protocol (OSAP) methodology (single-pass electrofishing with no block nets). Additional information about the various programs can be found in Table 1 and Appendix A. - Reporting of fish community state is typically done using a modified Index of Biotic Integrity (IBI) approach that varies with each CA. IBI are typically composed of several metrics (e.g. species diversity) which compares the sampled result to an expected healthy assemblage. - There have also been at least two reports that summarized fish assemblages across this area that employed a multivariate approach to summarizing and reporting on state that utilized a modified reference condition approach (hindcasting). Additionally, the collaborative has been collecting extensive data for use in assessing diagnostic states of streams and to assist with understanding causal pathways. There are hundreds of datasets from continual temperature loggers that have been collected at both the fisheries sites described above as well as at some hydrology sites. Many of the agencies have also established continual monitoring discharge stations to augment the HYDAT data in their watersheds. Fluvial geomorphology data is also available from within the CVC and TRCA watersheds, although this data does not explicitly overlap with the fisheries data. Finally, spot flow discharge data, especially related to baseflow is available from most of the study area. 1 Jon Clayton (CVC), Andrea Dunn (HRCA), Dave Lawrie (TRCA), Dan Moore (CLOCA), Brian Morrison (GRCA), Les Stanfield, Angela Wallace (TRCA), Rob Wilson (LSRCA)

2 Table 1. Synopsis of fisheries data available for spatial and temporal analysis on fish assemblages from the SOSMART area Organization Start Year (cycle) # Longterm sites # Single observation sites Study Design HRCA 2005 (2) 100 Targeted representative plus seine and other fish presence data TRCA 2000 (3) 150 ~350 Stratified random, matched with benthic and channel morphology data CVC 1999 (2) 25 ~ 300 Semi-random and targeted, picked up historic site, from 3-15 years of sampling LSRCA 2002 (1) 50 ~ of the trend sites have only 4 years sampling; stratified random and some targeted; all sites also have channel morphology data (repeated every five years) CLOCA 1998 (1&5) sites sampled annually, plus 5 that are sampled during OSAP training, GRCA 2002 (1) 10 ~150 Note 5 sites were historically sampled by MNR 1 and have data back to Note: In addition, Ontario Ministry of Natural Resources and Forestry (OMNRF) salmonid ecology unit collected approximately 500 sites worth of fisheries and habitat data throughout the SOSMART area from Discussion The five main questions discussed by the group are listed below. The challenges and needs required to address each of these themes was discussed in detail with the intent of beginning to identify steps for moving forward as a group or in partnership with researchers. 1. What is the state of the fish communities in each watershed and does this change spatially within a watershed? 2. What are the spatial and temporal trends in key indicators and rare species? Is there synchrony? 3. What are the temporal trends in the fish assemblages? 4. How important are noise factors in masking trends in fish assemblages? 5. Are measures of channel morphology and digital temperature data effective as either early warning or diagnostic indicators of fish assemblage state? Measuring Fish Community State The advantages and disadvantages of using an IBI in comparison to a multivariate approach for summarizing fish assemblages were discussed. This long standing debate is also a hot topic in current literature and the group agreed to continue to share recent papers on the debate. One disadvantage of using the IBI approach is that the metrics cannot accommodate the fact that the fish assemblages vary along a natural gradient from source to outlet. Researchers have attempted to accommodate this by developing indices for specific habitats, (e.g. coldwater or warmwater IBIs), but there is no independent means of determining where one verses the other should be applied. Rather the index assumes that one type of assemblage is inherently better than another. Further, as applied in southern Ontario the IBI will need to resolve how non-native (and possibly stocked) fish such as Brown and Rainbow Trout and invasive species such as Round Gobies are treated.

3 The advantages for using IBI metrics is heavily influenced by the ease in which the information can both be summarized and communicated to the general public. Alternative approaches include using multivariate statistics which are often difficult to understand. Complicating this debate is the challenge of setting benchmarks of healthy states within watersheds. Locally modified IBI metrics enable benchmarks to be adjusted so that measures of state reflect local areas of degradation. With this approach similar fish assemblages in different watersheds could receive quite different ratings of their states. It became clear that these two issues are intertwined and will need to be addressed if a consistent measure of fish state is to be applied across the study area. One solution that was proposed is to use a two-step approach, the first being to measure all streams using the same measure of deviation from expected. The second step reflects local values and targets of how far a deviation is from the goal for a watershed. In this way, a measure of X in any watershed would reflect a similar measure of state, but the number could be interpreted differently depending on local targets. The degree to which such a solution could work depends largely on the ultimate metric that is developed/agreed upon for use in the area. Whichever approach is applied to develop a consistent and meaningful metric for summarizing fish assemblages will require an ability to: - Address the contentious issue of the presence of non-native fish in a site; - Include rare fish in the summary statistic; - Determine some measure of the reference state of a stream that reflects its position in the watershed; and - Be a sensitive and robust measure of change across time and space in fish assemblages. Spatial and Temporal Trends in Key Indicator Species and in Fish Assemblages The group expressed a desire to report on trends for several key indicator species across the region, some of which are believed to be in decline (e.g. Brook Trout, Slimy Sculpins, Rainbow Darters) or are expanding (Round Gobies, Green Sunfish). The suggested first step is to collect and map the current verses historic ranges of a number of key species. Issues were identified such as data not being contained in one central location. Although FWIS contains a large amount of data, it is not mandatory that fish data is entered into it. Several CAs do not use FWIS and much of the data collected by independents (e.g. consultants, researchers) is not entered in the database either. It is mandatory to supply fish collection records to the local OMNRF office which granted the licence to collect fish for scientific purposes but much of this data is not electronic. Further effort to centralize and digitize data is needed. The group also acknowledged that for much of the study area, there is a gap in the datasets for headwater fisheries (e.g. first and second order streams). Future sampling might consider targeted sampling of these headwater features. For now their omission should be explicitly stated as a limitation of any analysis. Value of early warning and diagnostic data To date, only limited analysis has been conducted on the value of digital temperature data and channel morphology data on fish assemblages (Stanfield et al 2006) and no temporal trends for been evaluated. There is now an extensive dataset for use in evaluating the degree to which these data help explain fish assemblage findings and or are informative on their own about the state of the streams. Such spatial and temporal analysis would also help inform future study designs about how frequently these types of data should be collected (i.e. how variable are they over time). Size and age data are not consistently measured across jurisdictions but is believed would offer an effective early warning indicator for some species if it were available. The group wished to explore the degree to which changes in size/age classes in a population provides a measure of its stability. Such effort would require a cost-benefit and sensitivity analysis to determine whether such information should become a part of the study design for fish

4 surveys. Such data does exist for salmonid communities across the study area and could provide a template for other species of interest. Understanding sources of variance in fish assemblage data Critical to measuring and understanding trends in fish assemblages is the ability to identify what is noise in a dataset from what might be the result of a meaningful action. The sensitivity and robustness of the metrics used to characterize fish communities will require analysis that partitions the various sources of variance. The group identified a number of potential sources of variance that could result in spurious changes in fish assemblages. Data is readily available to test the importance of each in fish assemblages and so the predictor variable has been articulated as a hypothesis for each as follows: 1. Equipment issues: Fish assemblages caught using different electrofishers (e.g. manual vs. automatic settings, Haltech vs. Smith Root) 2. Surveys conducted in different seasons will capture different fish assemblages 3. Documented changes in site morphology will result in measureable changes in fish assemblages 4. Differences in the timing and magnitude of winter flow events are reflective of measured fish assemblages in the following season 5. Variation in effort expended at a site is sufficient to effect summary statistics for a site 6. A single OSAP site is insufficient to characterize the fish assemblages within a stream segment 7. There is a difference in fish assemblages based on whether they have been selected based on random, targeted or representative study design rules 8. Seining a site will generate a different fish assemblage than will electrofishing Note the metadata associated with each survey event is part of the Flowing Water Information System (FWIS) database. Some of this data has not been included during data entry and CA staff should work toward including this data in the database (data already in database as well as future data entry). Another emerging issue that CAs are grappling with is how to best incorporate other survey methods such as seine netting into long-term monitoring programs. While there is now an OSAP module to describe how to document seining survey results, the guidance for when this technique should be used and how the results should be incorporated into an overall summary of a fish assemblage are unclear. Data are not yet available to address this hypothesis but the group agreed that it should be an active area of research. Conclusions The group expressed a strong desire to work towards comparable and better integrated approaches to summarizing and reporting on fish assemblages. There was also a desire to look at the data on a wholistically rather than CA by CA. As a first step, it was suggested that existing fisheries data be explored to determine the current verses historic distribution of all species found in the study area. As a second step, monitoring data should also be explored and mapped on a site by site basis to determine trends in abundance over time for all species for which the data is available. Once an agreed upon approach for summarizing the fish assemblage data is established, a similar set of graphs and maps should be generated using this new metric. Next steps included seeking other partners that might be interested in this discussion and determining a set of possible reference sites. There was hope that this effort could dovetail with the ongoing biocriteria project currently underway with benthic communities. Finally, it was agreed that before any analysis or research could be undertaken that the gaps in fisheries data within FWIS must be addressed.

5 ACTION ITEMS: 1. All CAs to check the metadata site selection criteria for their individual sites in FWIS. When data from HABPROGS (previous database) were imported into FWIS, all were assigned as random but the discussion pointed out that many sites were chosen for a specific reason and are not random. 2. CVC to check if 2013 fish data was uploaded to FWIS. 3. Les to ask Antoine Morin (University of Ottawa) to circulate a presentation about sensitivity of BMI indices.