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Lessons for Formosan landlocked salmon conservation from the long-term ecological monitoring at Wuling
Author: Hsing-Juh Lin(Department of Life Sciences, National Chung Hsing University)
Shei-a National Park, located in northern part of central Taiwan, has rich wildlife and natural resources. The Formosan landlocked salmon (Oncorhynchus masou formosanus) of the Wuling area on the upper reaches of the Dajia River is well known. The salmon is a relic species from the Ice Age and is a landlocked cold zone species of salmon but lives in tropical/sub-tropical Taiwan. It is one of the only types of salmon in the world distributed so far south and was a major biological/geographical discovery. Around 50 years ago Formosan landlocked salmon could be found in the six tributaries of the Dajia River catchment area. However, development of agriculture, the building of sediment dams and typhoon floods and other factors brought about dramatic change in the salmon habitat. Today the salmon ‘s distribution is limited to Qijiawan River, Gaoshan Creek, Taoshan West Stream and Taoshan North Stream and its survival is seriously threatened.

In 2004 Professor Lin Xin-zhu of the Department of Life Sciences of National Chung Hsing University formed the Wuling Long-Term Ecological Research and Modeling(WLTERM) research team. 12 project directors from various disciplines joined the team from: The Department of Life Sciences, National Chung Hsing University, Biodiversity Research Center and Research Center for Environment Changes, Academia Sinica, Department of Entomology, National Chung Hsing University, Department of Soil & Environmental Sciences, National Chung Hsing University, Department of Life Sciences, National Tsing Hua University, Institute of Wildlife Conservation, National Pingtung University of Science & Technology, Department of Water Resources Engineering & Conservation, Fengchia University, Department of Environmental Resources Management, Transworld Institute of Technology and Department of Environmental and Safety Engineering, Mingchi University of Technology. In accordance with food webs Qijiawan related research topics were integrated and samples taken at the joint stations at the same time, monitoring of water temperature, flow, physical habitat, water quality, algae, terrestrial and aquatic insects, amphibians and mammals, birds and bird temporal and spatial changes was carried out and the long term objective of establishing different scale ecological models was set. Establishing of species composition and richness changes and other basic quantitative information for the area began and at the same time, river bank farming activity, habitat and water quality monitoring was carried out. In6, in addition to continuing long-term ecological monitoring in the Wuling area for the establishment of medium elevation mountain stream ecological modeling models, the data from the past 20 years of monitoring of Formosan landlocked salmon was compiled and a salmon age population matrix with population scale was completed. In 2007 WLTERM expanded and integrated the quantitative data collected on other aquatic creatures over the previous two years, completing river ecosystem model and a food chain energy flow and nutrient flux and breathing model for the Wuling area. Examination of the impact of typhoon floods on habitat and the aquatic creatures also began. A model was used to calculate that the ecological load for the Formosan landlocked salmon in the Wuling area is 4,600 fish, close to the figure record high population of the fish of 5,321 recorded in 2008.The research project also found that the removal of the sediment dam on Gaoshan Creek, a tributary of Qijiawan River has had a positive effect on the salmon by improving the environment. This kind of information, backed up by real data, is rare internationally and this finding became the subject of a cover article in an edition of Zoological Studies. In 2008, in addition to continuing with ecological monitoring work we have also completed the following works.

1. Measuring of the residual pesticide, environmental hormones and heavy metals in Formosan landlocked salmon and goby [Formosan landlocked salmon and Formosan Kooye Minnow(Varicorhinus barbatulus.)] tissue.
2. Integration of river bioorganic and environmental factor data collected by all sub-programs 2005-2008 to understand the driving forces behind the changes in the river ecosystem.
3. Different data oriented models - Habitat Evaluation Procedure and Data Clustering Algorithm have been used to describe the relationship between salmon fry and impact factors and combination forecasting using different types of regression analysis and back-propagation neural network carried out.
4. An ecological data bank for the Wuling area has been established.

With regards to measuring pesticides, Nonylphenol (NP) and heavy metal mercury, no residues of the 195 pesticides announced by the Department of Health were detected in the tissue and livers of the salmon or goby [Formosan landlocked salmon and Formosan Kooye Minnow(Varicorhinus barbatulus.)]. No NP or NPEO (Nonylphenol Ethoxylates ) residues were detected either. The detection limits were 10ppm and 20 ppm. Only a small amount of mercury residue was found, 0.062 ppm in the tissue and only 0.066 in the ovaries of the salmon.

We, at the same time, carried out integrated analysis of the relationship between temporal and spatial distribution, environmental factors and body shape (adult, sub-adult, fry) data for different species of fish [Formosan landlocked salmon and Formosan Kooye Minnow(Varicorhinus barbatulus.)] collected 2005-2008 over long-periods by five fixed monitoring stations on Wuling area rivers (Taoshan West Stream, No.1 dam, fish farm, Gaoshan Creek and Yousheng River). Redundancy analysis (RDA) direct gradient analysis results showed that the first two axis were 0.342 and 0.092, together explaining around 44% of the variance of the fish population and around 84% of the variance of environmental and other biological factors. Algae amount, SO4-2 level, gravel proportion and water temperature were the best for explaining different fish species and body type distribution differences.

We found that Formosan landlocked salmon population, whether adult, sub-adult or fry had a negative correlation with aquatic insect numbers, sulphite level and conductivity but had a positive correlation with bird numbers, deep rapids and small and large sized gravel proportion. High proportion of deep rapids and large and small gravel are the special habitat features of the Taoshan West Steam and No.1 dam monitoring stations. Goby population, whether adult, sub-adult or fry, had a positive correlation with water temperature, small stone proportion, algae quantity and nitrogen nutrient (NO2+ NO3) density, however there was a negative correlation between small stone and flow property and Biochemical Oxygen Demand (BOD).High water temperature, high small stone proportion, large amount of algae and nitrogen nutrient density are the special habitat features of the Yousheng River monitoring station.

Using HEP and GMDH algorithm prediction models, Back-propagation Neural Network was used to carry out Combination Forecasting and the results showed the factors affecting fry number forecasting in summer were: The number of Formosan Kooye Minnow(Varicorhinus barbatulus), the number of aquatic insects, conductivity, BOD, sulphite density, organic carbon density, nitrogen nutrient density (NO2+ NO3), chloride ion density, water temperature, small stone proportion, stone proportion and small pebble proportion and the number of adult salmon the previous winter. The factors affecting winter fry numbers were: pH, conductivity, BOD, sulphite density, organic carbon density, water temperature, water flow speed, small stone proportion, shingle proportion, stone proportion, small pebble proportion, large pebble proportion, tranquil flow, shallow rapids and deep rapids proportion. It was also discovered that pH, organic carbon density, small stone proportion, large pebble proportion and deep rapids proportion were relatively sensitive in terms of forecasting winter fry number. Compared to the summer fry forecasting method it can be seen that the influence of the environmental factor large pebble proportion on winter forecasting of fry number increased greatly. Summer and autumn typhoon floods are key factors deciding the survival of fry and maybe large sized pebbles can provide shelter for fry in the floods

Using the research results of the past four years, the integration plan has established various ecological monitoring methods for medium elevation mountain rivers and has developed a monitoring system for the area made up of three biological monitoring systems, the TDI and DAIpo Bacillariophyceae indexes, water insect index and WWQI (Wuling Water Quality Index: conductivity, turbidity, Biochemical Oxygen Demand (BOD), total phosphate and ammonia nitrogen as the monitoring factors.) In the future, an integrated ecological indicator based on endemic species research can be further developed. At the same time, a clear understanding of the impact of river bank farming activities, typhoon floods and water temperature on river biorganisms has been acquired and ecological models of different scales for population and water food web. The Wuling ecological data bank established by the program has collected 55608 pieces of biological data, from 670 species in 363 families, 99 orders and from 15 webs, 217 pieces of water quality data, 401 pieces of algae and organic fragment data and 1369 pieces of flow simulation data (http://wlterm.biodiv.sinica.edu.tw).

Our suggestions for the scientific data based ecological management of Wuling thus are:

1. Pesticides and NP are not the main factors affecting the Formosan landlocked salmon population and monitoring focus should be on changes in habitat factors.
2. Overall statistical analysis shows that the main factors affecting the Formosan landlocked salmon population are water temperature, flow, size of substrate particles, habitat type and water quality. A whole catchment area monitoring system needs to be established to carry out long-term ecological monitoring.
3. Riverbank vegetation should be actively restored because this will help lower the water temperature, reduce torrential rain run off and filter river bank nutrient salt and organic carbon.
4. Subsrate large sized pebble proportion is more important for predicting winter fry numbers than for predicting summer fry numbers showing that large sized gravel plays an important role by providing a shelter for fry in after heavy summer typhoon rains. Therefore adding large pebbles can be considered as one of the main ways of improving the salmon habitat.
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Last Update Date:2017-03-29
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