Timothy B Grabowski

Timothy B Grabowski
United States Geological Survey | USGS · Cooperative Research Units Program

Ph.D. Zoology

About

64
Publications
11,288
Reads
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636
Citations
Additional affiliations
June 2016 - present
U.S. Geological Survey
Position
  • Unit Leader
June 2016 - present
University of Hawaiʻi at Hilo
Position
  • Professor
April 2012 - present
Oklahoma State University - Stillwater
Position
  • Research Assistant
Education
May 2002 - May 2006
Clemson University
Field of study
  • Zoology
May 1999 - December 2002
Texas A&M University
Field of study
  • Wildlife and Fisheries Science
January 1996 - May 1999
Texas A&M University - Galveston
Field of study
  • Marine Fisheries

Publications

Publications (64)
Article
Full-text available
Habitat heterogeneity at multiple scales is a major factor affecting fish assemblage structure. However, assessments that examine these relationships at multiple scales concurrently are lacking. The lack of assessments at these scales is a critical gap in understanding as conservation and restoration efforts typically work at these levels.A combina...
Article
Full-text available
The physical habitat used during spawning may potentially be an important factor affecting reproductive output of broadcast spawning marine fishes, particularly for species with complex, substrate-oriented mating systems and behaviors, such as Atlantic cod Gadus morhua. We characterized the habitat use and behavior of spawning Atlantic cod at two l...
Article
Full-text available
There is increasing recognition of intraspecific diversity and population structure within marine fish species, yet there is little direct evidence of the isolating mechanisms that maintain it or documentation of its ecological extent. We analyzed depth and temperature histories collected by electronic data storage tags retrieved from 104 Atlantic...
Article
We used stable isotope analysis to investigate differences in Guadalupe bass (Micropterus treculii) resource use that might be associated with population‐level variation in mainstem river versus tributary stream habitats. Guadalupe bass from mainstem sites had higher δ13C and δ15N values compared to those collected in tributaries, likely reflecting...
Article
Full-text available
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, subs...
Technical Report
Full-text available
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 account...
Article
Full-text available
Alteration of flow regimes by anthropogenic activities is one of the primary environmental problems in riverine systems. Understanding how hydrologic conditions can affect ontogenetic habitat shifts of imperiled fishes is important in order to develop conservation and management strategies for each life-history stage. We examined relationships betw...
Article
Full-text available
Predicting how stream fishes may respond to habitat restoration efforts is difficult due, in part, to an incomplete understanding of how basic biological parameters such as growth and ontogenetic habitat shifts interact with flow regime and riverscape ecology. We assessed age-specific Guadalupe Bass Micropterus treculii habitat associations at thre...
Article
• 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...
Conference Paper
Full-text available
Background/Question/Methods (184/200 words): For effective conservation, managers first must understand where species occur. A useful tool for understanding species ranges are species distribution models (SDMs), which make predictions by relating occurrences with environmental factors. SDMs assume that occurrence data provide an accurate representa...
Chapter
This chapter details the early life history of the Atlantic cod starting at fertilization through larval development and continues with the descent of a juvenile cod from the plankton to suitable nursery habitat on the seafloor. It also covers the early years, from habitat use to growth, diet, mortality and behaviour, and ends as the juvenile cod b...
Article
Full-text available
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 morph...
Article
Full-text available
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 lo...
Article
Full-text available
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 sn...
Technical Report
Full-text available
Giant Trevally (ulua aukea) Caranx ignobilis is one of the most highly prized and frequently targeted nearshore species. However, there is very little information on its current status in Hawaiian waters. This study uses mark-recapture data collected as part of recreational angler tagging program conducted by the Hawaii Department of Land and Natur...
Article
Full-text available
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...
Article
Full-text available
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,...
Research
Full-text available
Grabowski T. B. 2016. Assessing the feasibility of using acoustic monitoring for Burbot conservation, management, and production. Report provided by the Cooperative Fish and Wildlife Research Unit Program under agreement with the U.S. Fish and Wildlife Service. U.S. Department of Interior, Fish and Wildlife Service, Cooperator Science Series FWS/CS...
Article
Full-text available
Accessing and effectively sampling the off-channel habitats that are considered crucial for early life stages of freshwater fishes constitute a difficult challenge when common ichthyoplankton survey methods, such as push nets, are used. We describe a new method of deploying push nets from jet-propelled kayaks to enable the sampling of previously in...
Article
Full-text available
Understanding the environmental processes determining the timing and success of reproduction is of critical importance to developing effective management strategies of marine fishes. Unfortunately it has proven difficult to comprehensively study the reproductive behavior of broadcast-spawning fishes. The use of electronic data storage tags (DSTs) h...
Article
Full-text available
Low-cost unmanned aerial systems (UAS) have recently gained increasing attention in natural resources management due to their versatility and demonstrated utility in collection of high-resolution, temporally-specific geospatial data. This study applied low-cost UAS to support the geospatial data needs of aquatic resources management projects in fou...
Conference Paper
Full-text available
Anthropogenic modification to riverine systems has reduced access to important off-channel nursery habitats. Some species utilize these floodplain habitats during early life history. The river-reservoir interface (RRI), a transitional zone between lentic and lotic habitats, may provide surrogate nursery habitats for these species. We sampled ichthy...
Conference Paper
Full-text available
Pecos Assiminea is an endangered, semi-aquatic snail endemic to two spring systems located in eastern New Mexico and west Texas. Basic biological information needed for effective monitoring and conservation is currently lacking for this species. Our objectives were to compare the effectiveness of surveys using two gear types, quadrats (n = 366) and...
Conference Paper
The reproductive strategies of many marine fishes rely heavily on the synchronization of gamete development and release. Lunar synchronisation of spawning is well documented in many tropical species though examples are rare in temperate waters. Here we explore the circulating levels of the primary sex steroids (11-ketotestosterone 17β-estradiol and...
Conference Paper
The Zebra Mussel continues to expand its range across North America despite varied efforts at containment and apparent physicochemical barriers. Early research had suggested that high water temperatures would prevent their spread and establishment in Texas. However new records in the reservoirs of the Trinity and Brazos River Basins in northern Tex...
Conference Paper
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 regards to spawning. We evaluated the relationship between morphology and habitat...
Article
Electronic data storage tags (DSTs) were implanted into Atlantic cod captured in Icelandic waters during 2002-2007 and the depth profiles recovered from these tags (females: n=31, males: n=27) were used to identify patterns consistent with published descriptions of cod courtship and spawning behavior. The individual periods of time males spent exhi...
Article
Full-text available
Habitat fragmentation and flow regulation are significant factors related to the decline and extinction of freshwater biota. Pelagic-broadcast spawning cyprinids require moving water and some length of unfragmented stream to complete their life cycle. However, it is unknown how discharge and habitat features interact at multiple spatial scales to a...
Article
Full-text available
Common Snook Centropomus undecimalis were once abundant off the Texas coast, but these populations are now characterized by low abundance and erratic recruitment. Most research concerning Common Snook in North America has been conducted in Florida and very little is known about the specific biology and habitat needs of Common Snook in Texas. The pr...
Article
Full-text available
Pelagic broadcast spawning cyprinids are common to Great Plains rivers and streams. This reproductive guild produces non-adhesive semi-buoyant eggs that require sufficient current velocity to remain in suspension during development. Although studies have shown that there may be a minimum velocity needed to keep the eggs in suspension, this velocity...
Conference Paper
Full-text available
Gray Redhorse Moxostoma congestum is native to upland streams from the Brazos River in Texas to the Río Soto La Marina in Tamaulipas, Mexico. Populations of gray redhorse are stable across much of its range, but habitat degradation associated with dewatering of streams has led to the decline of some populations in the western portion of its range....
Article
Stratification restricts habitable areas forcing fish to balance between favourable temperature and minimum dissolved oxygen requirements. Acoustic surveys conducted during the stratified and isothermal periods on tropical Lake Victoria indicated that stratification of temperature and dissolved oxygen (DO) affected vertical distribution of Nile per...
Article
Conservation efforts for threatened or endangered species are challenging because the multi-scale factors that relate to their decline or inhibit their recovery are often unknown. To further exacerbate matters, the perceptions associated with the mechanisms of species decline are often viewed myopically rather than across the entire species range....
Article
Quantitative studies focusing on the collection of semibuoyant fish eggs, which are associated with a pelagic broadcast-spawning reproductive strategy, are often conducted to evaluate reproductive success. Many of the fishes in this reproductive guild have suffered significant reductions in range and abundance. However, the efficiency of the sampli...
Data
Video of Atlantic cod captured by a dual-frequency identification sonar (DIDSON) deployed approximately 1.0 km off the coast of Iceland at Knarrarós on 15 April 2009. The DIDSON is positioned approximately 10 m off the bottom fur the duration of the video. During the initial part of the video, the DIDSON is oriented at a 30° angle off perpendicular...
Article
Full-text available
Riverine catostomids can show a wide range of interspecific variation in life-history characteristics. Understanding these differences is an important consideration in evaluating the sensitivity of these fishes to disturbance and in formulating effective conservation strategies, particularly when dealing with an assemblage consisting of multiple sp...
Article
This study investigated the development of a quantitative method for distinguishing stock components of Icelandic cod Gadus morhua based on visual examination of morphology. The stock is known to be structured into genetically distinct geographic components (north and south of Iceland) and behavioural types that spawn sympatrically. Differences in...
Article
a b s t r a c t Spatial distribution is increasingly studied using individual based telemetric methods in lieu of, or sup-plementing, surveys. Distributions may be in two-or three-dimensions, or in an abstract space such as depth-temperature space. One of the most basic questions one might address when analyzing these data is whether the distributi...
Conference Paper
Quantitative studies focusing on the collection of semi-buoyant fish eggs, associated with a pelagic broadcast-spawning reproductive strategy, are often conducted to evaluate reproductive success. Many fishes represented in this reproductive guild are considered threatened or endangered. However the efficiency of the sampling gear used to evaluate...
Conference Paper
Arkansas River shiner (ARS) Notropis girardi, a federally threatened species is a small cyprinid native to rivers in the Great Plains ecoregion. It is a member of a reproductive guild of pelagic-spawning cyprinids inhabiting the rivers of the Great Plains. This species releases non-adhesive, semi-buoyant eggs during an extended spawning season. The...
Article
Full-text available
We document the discovery of Highfin Carpsucker in the Apalachicola River, FL. Three specimens were captured between river kilometer 170–171 on the Apalachicola River in the vicinity of Jim Woodruff Lock and Dam during spring 2007, The specimens were captured within a reach 0.5–1.0 km downstream from the dam and just upstream from a major spawning...
Article
Full-text available
Phenotypic plasticity and local adaptations are important considerations in delineating population structure of marine fishes and critical to their conservation and management. We compared the weight-specific oxygen consumption rates (VO2/M) of juvenile cod from the northern and southern components of the Icelandic stock acclimated to 4.0°C, 8.5°C,...
Article
Full-text available
Conservation and management of riverine species, such as the robust redhorse Moxostoma robustum, can be hindered by incomplete understanding of their population status. Behavioral responses to sampling methods and susceptibility to capture by a particular gear type have implications for the reliability of population assessments yet are rarely evalu...
Article
1. Robust redhorse Moxostoma robustum is an imperiled, potadromous fish in the south-eastern USA. Initial recovery efforts have focused on supplementing existing populations and establishing refugial populations through extensive stocking programmes. However, assessment of the success of these programmes has not yet been conducted, and there are fe...
Article
Full-text available
Little is known about the behavior of individual fish in a spawning aggregation, specifically how long an individual remains in an aggregation. We monitored Moxostoma robustum (Cope) (Robust Redhorse) in a Savannah River spawning aggregation during spring 2004 and 2005 to provide an estimate of the total number of adults and the number of males com...
Article
Full-text available
Abstract –  Differences in the life history strategies employed by otherwise ecologically similar species of a fish assemblage may be an important factor in the coexistence of these species and is an essential consideration in the conservation and management of these assemblages. We collected scales to determine age and growth of four species of th...
Article
Full-text available
Little is known about the behavior of individual fish in a spawning aggregation, specifically how long an individual remains in an aggregation. We monitored Moxostoma robustum (Cope) (Robust Redhorse) in a Savannah River spawning aggregation during spring 2004 and 2005 to provide an estimate of the total number of adults and the number of males com...
Article
Full-text available
Shallow-water, lithophilic spawning fishes are among the most vulnerable to anthropogenic fluctuations in water levels. We monitored water levels and environmental conditions at the nest sites of Moxostoma robustum (Robust Red-horse) on a main-channel gravel bar in the Savannah River, GA–SC. During the course of the 2005 spawning season, over 50% o...
Article
Spawning aggregations of five species of catostomids were observed on the two mid-channel gravel bars of the Savannah River, Georgia and South Carolina, in 2004 and 2005 to assess the degree of spatial and temporal overlap in the use of this habitat and determine the habitat preferences leading to segregation. Spawning catostomids showed a consider...
Article
Full-text available
We assessed fish escapement from two South Carolina reservoirs, Par Pond and L Lake, from spring 2002 through summer 2003. Escapement was greatest in the spring and early summer, with lake chubsucker Erimyzon sucetta dominating the escapement catch in early spring and several sunfishes Lepomis spp. dominating in late spring and early summer. Most o...
Article
Full-text available
The robust redhorse Moxostoma robustum is a large riverine catostomid whose distribution is restricted to three Atlantic Slope drainages. Once presumed extinct, this species was rediscovered in 1991. Despite being the focus of conservation and recovery efforts, the robust redhorse's movements and habitat use are virtually unknown. We surgically imp...
Article
Full-text available
We investigated the potential of prepositioned grid electrofishers as a means of collecting broodstock for the rare robust redhorse Moxostoma robustum. We found that combined with visual observation, this technique allowed for the efficient capture of fish in breeding condition. We were able to harvest eggs in the field and bring only fertilized eg...
Article
Full-text available
Flathead catfish were introduced to the Altamaha River system, Georgia in the 1970's. We determined the length-weight relationship, Von Bertalanffy growth parameters, and back calculated lengths by examining the sagittal otoliths of 331 individuals captured from this population. We found that there were no sex related differences in length weight r...
Article
Full-text available
One alternative reproductive tactic involving early-maturing, cryptic males is referred to as “sneaking.” Although sneakers tend to be easily detectable upon close inspection, little is known about the proportion of a fish population consisting of sneakers. We examined 15,400 age-1 rainbow trout Oncorhynchus mykiss in a hatchery. Total length (mm),...
Article
Full-text available
Large-format visible implant alphanumeric (VIalpha) tags were implanted into 15,400 rainbow trout Oncorhynchus mykiss. Tag retention after 25 d was 82.6%, and survivorship was 92.8%. The results of this study compare favorably with those of similar studies on other species and suggest that large-format VIalpha tags are an appropriate choice for stu...
Article
Thesis (M.S.)--Texas A & M University, 2002. Includes bibliographical references (leaves 70-75). Vita. "Major subject: Wildlife and Fisheries Sciences."

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