Globally, rivers are increasingly being subjected to various levels of physical alteration and river regulation to provide humans with services such as hydropower, freshwater, flood control, irrigation and recreation. Although river regulation plays an important role in modern society, there are potential consequences which may negatively affect fish and fish habitat. While much effort has been expended examining the response of fish to fluctuating flow regimes in different systems, there has been little in the way of a comprehensive synthesis. In an effort to better understand the effects of river regulation on fish and fish habitat, we conducted a systematic review of available literature with three goals: (1) summarize the various research methodologies used by regulated river researchers, (2) summarize the effects found on fish and fish habitat and (3) identify opportunities for future research. The results of the synthesis indicate that a wide variety of methodologies are being employed to study regulated river science, yet there is a gap in incorporating methodologies that examine effects on fish at a cellular level or those techniques that are interdisciplinary (e.g. behaviour and physiology). There is a clear consensus that modified flow regimes in regulated rivers are affecting fish and fish habitat, but the severity and direction of the response varies widely. Future study designs should include methods that target all biological levels of fish response, and in which detailed statistical analyses can be performed. There is also a need for more rigorous study designs including the use of appropriate controls and replicates. Data on physical variables that co-vary with flow should be collected and examined to add explanatory power to the results. Increased multi-stakeholder collaborations provide the greatest promise of balancing ecological concerns with economic needs.

A study was conducted on bonefish Albula vulpes in The Bahamas to assess the utility of portable physiological diagnostic tools (i-STAT analyser with E3þ ion and haematology cartridge, ACCU-CHEK glucose meter and Lactate Pro lactate meter) for field physiology applications in remote locations. Physiological values derived from portable diagnostic tools were significantly related to values obtained from standard laboratory techniques [glucose (r 2 ¼ 0Á96), packed cell volume (PCV; r 2 ¼ 0Á33), Na þ (r 2 ¼ 0Á28), K þ (r 2 ¼ 0Á71) and Cl À (r 2 ¼ 0Á15)]. Actual values (i.e. intercepts), however, tended to deviate slightly between the two techniques. Nonetheless, these tools showed promise for documenting relative differences among fishes experimentally exposed to treatments inducing different levels of 'stress'. These tools were then used to characterize the effects of different capture techniques on the stress response of A. vulpes. Albula vulpes captured in seines and then temporarily held in pens were physiologically sampled between 1 and 45 min postcapture to evaluate postcapture stress dynamics. Blood glucose and lactate as well as PCV and haemoglobin (Hb) increased rapidly after capture but stabilized at maximal values by c. 20 min postcapture. When angled, larger A. vulpes took longer to exhaust and land than did smaller individuals. In addition, there was a positive relationship between the magnitude of increase in lactate and the duration of the angling event, implying that anglers can reduce stress by minimizing the duration of the fight. Fish sampled before and after a simulated angling treatment displayed clear increases in blood lactate, K þ , PCV and Hb, providing some of the first data on how individual A. vulpes respond to angling stress. In summary, this study revealed that techniques are now available for conducting field physiological studies on A. vulpes and possibly other species in remote locales, and that haematological and biochemical indicators of physiological disturbance vary with the intensity of the angling event.