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Tim Grabowski, PhD

Unit Leader - Hawaii Cooperative Fish and Wildlife Research Unit

​​​​​​​Research Interests

Tim is interested in the behavioral and physiological ecology of fishes and applying these fields to management and conservation issues. His research tends to focus on the reproductive ecology of fishes as well as local adaptation and population structuring.

Teaching Interests

Tim currently teach field ichthyology and foundations of ecology and conservation biology at Texas Tech University. He also teaches a summer course at the University of Iceland examining the effects of anthropogenic impacts, such as climate change and commercial fisheries, on the marine environment.

Professional Experience

  • Unit Leader, Hawaii Cooperative Fishery Research Unit, 2016-

  • Assistant Unit Leader, Texas Cooperative Fish and Wildlife Research Unit, 2010-2016

Education and Certifications

  • Ph D Clemson University 2006

  • MS Texas A&M University 2002

  • BS Texas A&M University 1999

Science and Products

Filter Total Items: 28

Mismatch between temperature and discharge disrupts spawning cues in a fluvial specialist, blue sucker Cycleptus elongatus

Seasonal movements cued by environmental variables are a critical component of riverine fish life history. Life-history events for species such as blue sucker Cycleptus elongatus are likely cued by discharge and temperature and may be disrupted if those life-history events and environmental regimes are mismatched. However, this effect may be dependent upon the habitat occupied when environmental c
By
Ecosystems Mission Area, Cooperative Research Units, Columbia Environmental Research Center

Blue sucker habitat use in a regulated Texas river: Implications for conservation and restoration

Species conservation requires a clear understanding of habitat availability and subsequent use of those habitats. In cases where species declines have occurred and gone undetected by conservation managers, habitat alteration, fragmentation, and loss are often the largest contributors. River fragmentation often results in altered flow regimes, subsequently impacting the availability of riverine hab
By
Ecosystems Mission Area, Cooperative Research Units, Columbia Environmental Research Center

Estimating detection and occupancy coefficients for the Pacific Islands coral reef fish species

The data-limited stock assessment models used to monitor the status of coral reef fish species in the Western Pacific region are dependent upon accurate estimates of standing stock biomass generated from underwater visual surveys of reefs. However, the imperfect detection of and variable occupancy of habitat by reef fishes are not currently accounted for in these estimates. Therefore, the objectiv
By
Cooperative Research Units

Looking for love under the ice: Using passive acoustics to detect burbot (Lota lota: Gadidae) spawning activity

Burbot (Lota lota: Gadidae) is a difficult species to manage effectively due to its preference for deep‐water habitats and under‐ice spawning behaviour, resulting in a poor understanding of its reproductive activity. However, the use of acoustic signalling by burbot as part of their mating system has recently been described and this behaviour may provide a means of investigating questions regardin
By
Cooperative Research Units

Early life history

No abstract available.
By
Cooperative Research Units

Changing environmental gradients over forty years alter ecomorphological variation in Guadalupe Bass Micropterus treculii throughout a river basin

Understanding the degree of intraspecific variation within and among populations is a key aspect of predicting the capacity of a species to respond to anthropogenic disturbances. However, intraspecific variation is usually assessed at either limited temporal, but broad spatial scales or vice versa, which can make assessing changes in response to long-term disturbances challenging. We evaluated the
By
Cooperative Research Units

Intraspecific differences in morphology correspond to differential spawning habitat use in two riverine catostomid species

Maintaining intraspecific diversity is an important goal for fisheries conservation and recovery actions. While ecomorphological studies have demonstrated intraspecific diversity related to feeding or flow regime, there has been little assessment of such variation in regard to spawning habitat. We evaluated the relationship between individual morphology of Robust Redhorse and Notchlip Redhorse and
By
Cooperative Research Units

Estimating factors influencing the detection probability of semiaquatic freshwater snails using quadrat survey methods

Developing effective monitoring methods for elusive, rare, or patchily distributed species requires extra considerations, such as imperfect detection. Although detection is frequently modeled, the opportunity to assess it empirically is rare, particularly for imperiled species. We used Pecos assiminea (Assiminea pecos), an endangered semiaquatic snail, as a case study to test detection and accurac
By
Cooperative Research Units

Comparison of the precision of age estimates generated from fin rays, scales, and otoliths of Blue Sucker

Evaluating the precision of age estimates generated by different readers and different calcified structures is an important part of generating reliable estimations of growth, recruitment, and mortality for fish populations. Understanding the potential loss of precision associated with using structures harvested without sacrificing individuals, such as scales or fin rays, is particularly important
By
Cooperative Research Units

Variation and plasticity and their interaction with urbanization in Guadalupe Bass populations on and off the Edwards Plateau

The Colorado River Basin in Texas has experienced major alterations to its hydrologic regime due to changing land and water use patterns. These anthropogenic influences on hydrologic variability have had major implications for riparian and aquatic ecosystems and the species dependent upon them. However, impacts are often assessed at a limited temporal and spatial scale, tending to focus on relativ
By
Cooperative Research Units

Effects of temperature, total dissolved solids, and total suspended solids on survival and development rate of larval Arkansas River Shiner

Decreases in the abundance and diversity of stream fishes in the North American Great Plains have been attributed to habitat fragmentation, altered hydrological and temperature regimes, and elevated levels of total dissolved solids and total suspended solids. Pelagic-broadcast spawning cyprinids, such as the Arkansas River Shiner Notropis girardi, may be particularly vulnerable to these changing c
By
Cooperative Research Units

What can volunteer angler tagging data tell us about the status of the Giant Trevally (ulua aukea) Caranx ignobilis fishery in Hawaii: revisiting data collected during Hawaii’s Ulua and Papio Tagging Project 2000-2016

Giant Trevally (ulua aukea) Caranx ignobilis is one of the most highly prized and frequentlytargeted nearshore species. However, there is very little information on its current status inHawaiian waters. This study uses mark-recapture data collected as part of recreational anglertagging program conducted by the Hawaii Department of Land and Natural Resources-Divisionof Aquatic Resources during 2000
By
Cooperative Research Units
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Exit Creek and a waterfall behind it

Studying The Influence of Streamflow Variability on Fish Populations to Understand Nutrient Transport in Hawaiian and Alaskan Streams in a Changing Climate

Ecosystems spanning the zones from “ridge-to-reef" and “icefield-to-ocean” are home to relatively high levels of biodiversity; serve as conduits of nutrients to sensitive coastal environments; and are culturally and economically important to local communities. These systems are smaller and have unique geological and streamflow properties compared to more typical river systems and, because of this...
By
Climate Adaptation Science Centers
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Studying The Influence of Streamflow Variability on Fish Populations to Understand Nutrient Transport in Hawaiian and Alaskan Streams in a Changing Climate

Ecosystems spanning the zones from “ridge-to-reef" and “icefield-to-ocean” are home to relatively high levels of biodiversity; serve as conduits of nutrients to sensitive coastal environments; and are culturally and economically important to local communities. These systems are smaller and have unique geological and streamflow properties compared to more typical river systems and, because of this...
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Image: Mai Hawaii

Impacts of Extreme Events on the Native and Nonnative Aquatic Species of Hawaiʻi Stream Ecosystem

Freshwater is a critical driver for island ecosystems. Climate change has fundamentally altered the water cycle in tropical islands. The changes in dynamic patterns of streamflow could result in the temporal and spatial difference in the riverine, estuarine, and coastal habitats that support native species. In particular, these habitats support the nine native aquatic species in Hawaiʻi at differe...
By
Climate Adaptation Science Centers
link

Impacts of Extreme Events on the Native and Nonnative Aquatic Species of Hawaiʻi Stream Ecosystem

Freshwater is a critical driver for island ecosystems. Climate change has fundamentally altered the water cycle in tropical islands. The changes in dynamic patterns of streamflow could result in the temporal and spatial difference in the riverine, estuarine, and coastal habitats that support native species. In particular, these habitats support the nine native aquatic species in Hawaiʻi at differe...
Learn More

Science and Products