Newly hatched larvae could survive two weeks on yolk reserves alone, but were capable of feeding immediately on Artemia salina if provided. Larvae were transferred to beakers of fresh, unfiltered seawater each day. All mortalities appeared due to a failure to completely shed their molt. Each stage, defined as the period between molting, lasted an average of 9 days, with specimens reaching the post-larval stage at day 35 at 11ᵒC. Both the morphological guide and the methods of egg incubation were utilized to guide the present experiment. In the second study from this era, John Wickins investigated the influence of food density, salinity, temperature, and stocking density on the growth rate and survival of P. platyceros. Larvae hatching from females were reared in environments of 13-16ᵒC and 30±1% salinity. Development to post-larva was achieved at 15-29 days, in contrast to the 35-day span for Price & Chew; this is likely due to the warmer culturing temperatures. The stocking density yielding the highest survival rate was 5 larvae per liter at temperatures 13- 15ᵒC. Other key observations were that the size of Artemia fed to larvae did not influence larval growth rate or survival, and while larvae were raised successfully at a range of temperatures, there is a possible trend of fewer post-larvae survivors with increasing egg incubation temperature .The final major study addressing spot prawn rearing built off of those above to define the environmental extremes in which P. platyceros can thrive. Reiterating the others’ findings, Kelly et al. observed the larval period to last 26 to 35 days at 9.5-12.0ᵒC. They also concluded that spot prawns show a maximum thermal tolerance of 21.0ᵒC and salinity tolerance down to 22%. Growth rate was increased in both larvae and post-larvae by supplementing Artemia nauplii with any of four unicellular algae species. Kelly et al. also includes extensive investigation of diets for enhancing post-larvae growth, metal greenhouse benches which can be an important reference for further analysis of aquaculture potential, but the scope of this study is limited to larval development.
The present study attempts to reaffirm that this species can develop in laboratory settings. Using an amalgamation of the environmental parameters and timelines defined above, spot prawn larvae were hatched from ovigerous females caught off the coast of San Diego, California and cultured to post-larvae . The current growth of the aquaculture industry in conjunction with the depletion of wild seafood stocks makes revisiting this prospective aquaculture species a timely endeavor. By culturing eggs to this critical developmental phase, this experiments aims to provide an updated assessment as to whether P. platyceros may be a viable native species for aquaculture along the Pacific coast. The filter screen of the kreisel was large enough to allow Artemia and powdered feed through to the outflow chamber. This made it impossible to conclude if water clear of food matter signified the larvae had consumed everything or if it had been flushed out. The water was typically clear before most feeds, regardless of the Artemia concentration in the prior feeding. Because of this, feed concentrations were increased to compensate for food lost through the filter and the 120k Artemia per day became a minimum guideline. For future, the filtering screen of tanks should be of a finer mesh so as to allow longer retention of Artemia. This may require more frequent tank cleaning, perhaps stressing larvae, but the tradeoff would be observation of true feeding rates, which is required for maximizing efficiency of feeding schedules and densities. Possible cannibalism was observed occasionally, potentially indicating insufficient feed levels. Victims were usually white or translucent in color, which made it hard to distinguish between a mortality or exuviate. Since many crustaceans ingest their exuviae, it is possible this was natural feeding behavior ; it is also possible that larvae were cannibalizing each other due to lack of satiety. The uncertainty of this observation and that this occurred in the presence and absence of food renders this inconclusive.
As Kelly and Price & Chew both observed that most mortalities occurred in ecdysis, it is likely that failure during the molting process caused mortality.In regards to investigating aquaculture potential, future research should include large scaler trials of laboratory rearing with a priority on higher stocking densities and food conversion ratios. Percent survival at higher densities is essential in determining farming feasibility. The developmental period observed here is within the faster end of the range defined in previous studies and it would be useful to know if warmer temperatures could speed up the process further without significant increase in mortality. This trial experienced a maximum temperature of 19.4ᵒC, with sustained 19ᵒC temperatures for up to seven hours. Though not quite at the 21ᵒC thermal maximum, this culturing environment was very different than their natural habitat. Local waters did not reach higher temperatures until about halfway through the trial, so it would be interesting to see what impact consistently elevated temperature has during earlier larval stages. Furthermore, limitations in tank design prevented observations of feeding rates or food conversion ratios. Another essential question for aquaculture is the source of new stock. It is unknown if female spot prawns spawn more than twice in a lifetime, which would result a high turnover of broodstock. Until farmed specimens reached female maturity at four to five years, broodstock would have to be supplied from the wild. It is prudent to learn more about the reproductive capacity of mature spot prawns in order to provide a consistent supply of hardy larvae. Can females spawn for more than two years? Can fecundity be increased or stabilized by environmental conditions or does it continue to decrease each consecutive spawning? Do specimens from San Diego have the same seven- to eight-year lifespan estimated in Alaskan prawns ? Will they spawn in captivity? These questions are critical in establishing any level of commercial production and would also provide valuable information for future management of the wild fishery.
Finally, Litopenaeus vannamei is currently the marine species shrimp with the greatest global production by mass . This results in a wealth of knowledge in regards to techniques for disease prevention, broodstock maintenance, and other marine species obstacles that will likely be applicable to spot prawns. Some of the procedures for the current study were directed by methods used with L. vannamei. Macrobrachium rosenbergii, known as giant river prawns, are a freshwater shrimp that is also farmed. Farming methods for freshwater species are very different, though of all shrimp species farmed at a commercial-scale, M. rosenbergii is genetically of closest relation to spot prawns. M. rosenbergii and P. platyceros are both of the infraorder Caridae, so this freshwater species may provide a stronger biological reference for production timelines and practices . It would be prudent to use both species in directing future research regarding P. platyceros.The medical marijuana movement began in the San Francisco Bay Area in the early 1990s in a climate of official repression. This movement represents the most successful branch of the forty-year old drug policy reform movement. Using oral histories, participant observation, and archival research this dissertation explores the genesis, growth, and transformation of the medical marijuana movement in California from 1990 until 2012. I theorize the longevity of prohibitionist ideology over the course of the twentieth century in chapter one. Chapter two narrates the social history of the drug policy reform movement and its three branches; marijuana policy reform, harm reduction, and anti-prohibitionism. The three branches are characterized by diversification, as new organizations form to pursue different areas of drug policy reform, and competition for funding, but they maintain cooperative relationships with each other. My ethnographic fieldwork uncovered three types of physical sites, rolling greenhouse tables which play important roles in recruiting, networking, and facilitating cooperation on campaigns. The context and political opportunity structures of the San Francisco Bay Area were crucial factors in the genesis of the medical marijuana movement, but that activism and civil disobedience were also necessary for the movement to form. Activists and organizations in the metro areas of San Francisco, Los Angeles and San Diego were able to shape different political opportunity structures that affected the regulation of medical cannabis dispensaries in each specific locale. Medical marijuana began as a social movement and then transformed into an industry by shifting from the field of social movement action to the field of commercial action. New types of participants, a perceived change in political opportunity at the national level, and a more prominent public profile typify this shift. The shift also contributed to a refocused federal campaign to dismantle the system of medical cannabis provision that activists and entrepreneurs built over the twenty-one year history of the medical cannabis movement in California.The four decades old drug policy reform movement is comprised of individuals and organizations working to liberalize drug policies and move away from the system of “punitive prohibition” that typifies current drug policy in the U.S. According to Blain this “campaign is a ‘movement’ in the sociological sense that it employs the conventional repertoire of contention .” Drug policy reform organizations have trained their efforts on a wide variety of policy arenas, including, marijuana decriminalization, needle exchange programs , medical marijuana, and decreasing the penalties for drug offenses. Over the years, the number of organizations has increased and the specific concerns of various organizations have fragmented. The movement is made up of advocacy and membership-based organizations , a shifting mass base, and wealthy benefactors. Although the movement is ideologically powerful and well funded, successful campaigns in the political arena are few and far between. The drug policy reform movement has encountered opposition from both parent groups opposed to drug policy liberalization , and, uniquely, resistance from government agencies such as the Office of National Drug Control Policy and the Drug Enforcement Administration. The various organizations in the movement focus on a variety of campaigns of local, state,and national scope, yet the two most successful forms of drug policy reform have been medical marijuana and needle exchange programs Medical marijuana has been the most successful form of drug policy reform. In early 2012, sixteen states and the District of Columbia, have laws that allow qualified people to use marijuana for medicinal purposes. Individual medical marijuana dispensaries, storefront locations that sell cannabis to qualified patients, operate openly in California, Colorado, Montana and Washington. Clandestine medical cannabis dispensaries have been opened in several other states including Nevada, Michigan and Oregon. Along with needle exchanges and safe injection facilities, medical cannabis dispensaries represent specific modalities of drug policy reform. Modalities are different from changes in drug laws and sentencing policies because they have a physical location and present an active challenge to prohibitionist policies. The drug policy reform movement uses a combination of legal change to alter drug laws it finds unfavorable and direct action to put new policy modalities in place. While legislative change occurs comprehensively through ballot initiatives and the adoption of new legislation, activists, organizations and providers institute change on the ground slowly through protracted interactions with law enforcement agencies and state and local governments.In the 1930s, Alfred Lindesmith became the first scholar to look critically at the harmful consequences of punitive drug policy. His work paved the way for later scholars who looked at the negative effects of a policy that some have characterized as “punitive prohibition” . In the 1940s, Mayor Fiorello LaGuardia of New York City organized a team of scientists to investigate the cannabis use and policy in the Big Apple in response to fantastic allegations put forth by the director of the Federal Bureau of Narcotics in the previous decade. In the 1960s and the early 1970s, sociologists Becker , Gusfield and Duster all looked at the symbolic content of drug prohibition and the role of social status in determining which types of drugs were prohibited. During the 1980s and 1990s, epidemiologists and other scholars concerned with the intersection of drug use and drug policy would develop the harm reduction approach in response to the AIDS epidemic . Beginning the 1990s, the racially discriminatory consequences of the war on drugs became a major area of inquiry for scholars of drug policy .