The American Fisheries Society Endangered Species Committee herein provides a list of all crayfishes (families Astacidae and Cambaridae) in the United States and Canada that includes common names; state and provincial distributions; a comprehensive review of the conservation status of all taxa; and references on biology, conservation, and distribution. The list includes 363 native crayfishes, of which 2 (⟨ 1%) taxa are listed as Endangered, Possibly Extinct, 66 (18.2%) are Endangered, 52 (14.3%) are Threatened, 54 (14–9%) are Vulnerable, and 189 (52.1%) are Currently Stable. Limited natural range continues to be the primary factor responsible for the noted imperilment of crayfishes; other threats include the introduction of nonindigenous crayfishes and habitat alteration. While progress has been made in recognizing the plight of crayfishes, much work is still needed.

Rates of biodiversity loss are higher in freshwater ecosystems than in most terrestrial or marine ecosystems, making freshwater conservation a priority. However, prioritization methods are impeded by insufficient knowledge on the distribution and conservation status of freshwater taxa, particularly invertebrates. We evaluated the extinction risk of the world's 590 freshwater crayfish species using the IUCN Categories and Criteria and found 32% of all species are threatened with extinction. The level of extinction risk differed between families, with proportionally more threatened species in the Parastacidae and Astacidae than in the Cambaridae. Four described species were Extinct and 21% were assessed as Data Deficient. There was geographical variation in the dominant threats affecting the main centres of crayfish diversity. The majority of threatened US and Mexican species face threats associated with urban development, pollution, damming and water management. Conversely, the majority of Australian threatened species are affected by climate change, harvesting, agriculture and invasive species. Only a small proportion of crayfish are found within the boundaries of protected areas, suggesting that alternative means of long-term protection will be required. Our study highlights many of the significant challenges yet to come for freshwater biodiversity unless conservation planning shifts from a reactive to proactive approach.

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The embryonic and postembryonic development of the endemic Tasmanian freshwater crayfishes of the genera Astacopsis and Parastacoides was studied and described in detail. The embryonic development was similar in the two genera and corresponded to that described for other Parastacidae and Astacidae, but a prominent change in the colour of the yolk that parallels embryonic development was also noted. The general development sequence of young from Stage 1 to Stage 3 in Astacopsis and Parastacoides is similar to that described for other parastacid, astacid and cambarid crayfishes, but major differences in development between Astacopsis and other crayfishes are an extra developmental stage as well as the timing of the development of the uropods. The postembryonic development in Astacopsis is different from that in other parastacids as well as astaciddcambarids in having retained some of the ancestral marine larval characters, and it is considered to be primitive. Given this new information, it is proposed that early development in freshwater crayfishes recapitulates the entire primitive decapod sequence of larval stages.

The life history of the semi-terrestrial burrowing freshwater crayfish Parastacoides tasmanicus tasmanicus was studied in the wet heathlands of south-western Tasmania. Data on seasonal reproduction, fecundity and growth were obtained from regular monthly sampling over a period of two years. The development of gonads, size at maturity, sexual dimorphism and reproductive condition were determined by detailed examination of changes in reproductive morphology and gonad condition. P. t, tasmanicus attains maturity at a relatively late age (3-5 years) and large size (25-30 mm carapace length) and has a long life span (< 10 years) and a slow and variable growth rate. The growth rate appears to be a function of cold water temperature and low-nutrient diets. Males reach sexual maturity at a smaller size than do females. Mating and spawning, which closely follow the female moult, occur in early autumn when males and reproductive females pair within their burrow systems; eggs are carried over winter and hatch early the following summer, and young remain attached to their mothers until mid summer. Mature females appear to exhibit a biennial moulting and breeding cycle, an apparently unique strategy among parastacid crayfish, which is probably a result of the cooler climate conditions in Tasmania.