Higher Recapture Rates Research Articles

The evaluation of passive integrated transponder (PIT) tags and visible implant elastomer (VIE) marks as new marking techniques for the bullhead

To test the reliability of PIT tags and VIE marks as new marking techniques for the bullhead Cottus gobio, different tagging treatments were assayed. The relatively high recapture rates suggest the applicability of both marking techniques for this small benthic fish species.

Stopover Ecology and Habitat Use of Migratory Wilson's Warblers

The conservation of long-distance migratory songbirds is complicated by their life-history characteristics and the spatial scales that they traverse. Events during migratory stopovers may have significant consequences in determining the population status of migratory songbirds. Using Wilson's Warbler (Wilsonia pusilla) as a focal species, we investigated effects of age and sex on stopover parameters during spring and fall migration. Variation in stopover patterns was predominantly sex related in spring and age related in fall. In spring, males appeared at study sites earlier than females, and they carried higher fat stores and had lower recapture rates and higher rates of mass gain. In fall, migratory passage overlapped temporally among age and sex classes, but young birds had lower fat stores, higher recapture rates, and longer stopovers than adults. Habitat use differed between spring and fall migration and was affected by the combination of age and sex. Wilson's Warblers appeared to prefer native willow habitat during spring migration. Agriculture field/edge habitats may have represented "sink habitats" because birds in these habitats tended to be immatures and had a lower rate of fat deposition and longer stopovers. The data suggest that immatures were particularly vulnerable to habitat disturbances at stopover sites during fall migration, probably because of their lower social status and inexperience with long-distance migration. We conclude that knowledge of intraspecific variation in migration strategies is important for effective management of stopover habitats for migratory songbirds.

Effects of rearing technique and fish size on post‐stocking feeding, growth and survival of European grayling, Thymallus thymallus (L.)

European grayling, Thymallus thymallus (L.), were reared by four different techniques: (A) in a natural pond without a supply of artificial diet; (B) in a net pen fed artificial dry diet; (C) in tanks fed artificial dry diet; (D) in tanks, and for 16 days before stocking, transferred to a diet based on mixed frozen natural food exclusively. Fish within groups C and D were also split into subgroups of large and small fish. Feeding, growth and survival of fish in the different groups were compared after stocking into three different stocking sites during the spring of 1994. The stocking sites consisted of a barren lake (Lake L), a second lake (Lake N) containing an allopatric perch, Perca fluviatilis L., population, and a barren man‐made pond. In Lake L, higher recapture rates and mean weights of stomach contents were obtained in fish reared in the natural pond and in the net pen. There were no differences in total recapture rate, or mean condition factor between small and large fish within groups C and D. In Lake N only five (0.5%) stocked grayling from rearing groups A and B were recaptured during the experiment and more fish from categories C and D were recaptured. This was probably related to size‐selective predation. In the pond, there were no differences in recapture rates or in mean weight of stomach contents between fish from any of the groups. In sample 1 (Lake N, 22 days after stocking), mean weight of stomach contents was higher in the larger fish within categories C and D but there was no difference in condition factor between the groups. In sample 1, mean condition factor of fish from the different groups varied markedly, being highest in Lake L followed by Lake N and the Pond. Fourteen out of 26 dead fish in the pond showed clinical symptoms of the bacterial disease ASA. Mortality was related to low initial condition factor at the time of stocking. No stocked grayling were recaptured from the two lakes in the last sample (June 1995).

Movements and Growth Rates of Yellow-Phase American Eels in the Annaquatucket River, Rhode Island

Abstract Eight hundred twenty nine yellow-phase American eels Anguilla rostrata, 160–740 mm total length (TL), were electrofished from 10 stations in the Annaquatucket River, Rhode Island. The eels were individually marked with liquid-nitrogen-cooled brands and released at the site of collection. Resampling yielded 200 recaptures (24%); eels were recaptured at 8 of the 10 stations after 1 year. Of all recaptures, 174 (87%) were from the station of release, indicating restricted movement by American eels from the collection sites. Stations associated with dams had higher recapture rates, but there was no significant relationship between percent recaptured and eel density, station size, or distance upriver. An annual growth rate (mean ± SE) of 29.9 ± 4.7 mm/year for all American eels was estimated for a 214-d growing season. The growth rate for eels longer than 399 mm TL, which have previously been shown to be female, was 62.10 ± 14.9 mm/year, 2.3 times greater than for eels less than 400 mm. Mean growth ra...

High recaptures and long sampling range of pheromone traps for fall web worm mothHyphantria cunea (Lepidoptera: Arctiidae) males

Newly emerged males ofHyphantria cunea (Drury) (Lepidoptera: Arctiidae), marked with different fluorescent colors, were recaptured by pheromone trapping. Three Uni-traps, baited with (3Z,6Z)9,10-epoxyheneicosadiene, (9Z,12Z,15Z)octadecatrienal, and (3Z,6Z)9,10-epoxyheneicosa-triene in a 1:10:1 ratio, total 6 mg/dispenser, were placed in a line 15 m apart, perpendicular to the dominant wind direction, and checked after 12, 36, and 60 hr. At dusk, releases of 10-25 males were made over distances from 30 to 250 m, during 4 periods over a soybean field (nonhost plant). Recapture rates were high; of a total of 176 males released, 115 were recaptured with 88% of these within 12 hours. Between 40 and 100% of males were recovered over shorter distances (30-150 m), and between 10-24% at longer distances (200 and 250 m). No other species or unmarked males were captured. The trapping period showed little effect on recaptures. The central trap of the three traps had somewhat higher catches, but the slope of the regression of recapture over distance did not differ among traps. There was a significant decline of recapture over distance (r=-0.56) for catches of individual traps but a large scatter. Summed recaptures per distance gave less scatter and hadr=-0.86, allowing calculation of the maximum sampling range (R s ) after 60 hr as 340 m with a 95% confidence interval of 190-710 m (regression of arcsin √p and √R). The area of sampling, found by integrating the probability function of recapture over distance, from the source to maximumR, was 7 ha. The high recapture rates and the longR,. compared to those in the literature for other taxa, indicate that pheromone traps are highly efficient sampling devices in this species.

Age and Survivorship of the Slider (Trachemys scripta) and the Mud Turtle (Kinosternon subrubrum) in a Mississippi Farm Pond

Freshwater turtles seem to consistently exhibit high rates of annual survivorship as adults (Iverson, 1991a), but patterns of survivorship are less consistent or less well known for juveniles. Several studies have shown that juvenile survivorship during the first several years of life was lower than in adults: Kinosternon flavescens in Iowa (Iverson, 1991b); K. subrubrum from South Carolina (Frazer et al., 1991a); and Chrysemys picta from Virginia (Mitchell, 1988), New York (Zweifel, 1989), and Michigan (Frazer et al., 1991b). Detailed data on juvenile survivorship are generally lacking for populations of other freshwater turtles. Even in the well-studied emydid Trachemys scripta, Frazer et al. (1990) reported only limited and inconclusive data for survivorship in juveniles. Iverson (1991b) has argued that at least among the kinosternids, a Type III survivorship curve best approximates the observed survivorship data, rather than the Type II curve (constant mortality) usually advocated for turtle species generally. I studied the annual survivorship of 103 juvenile T. scripta for up to 7 yr of age, obtaining high recapture rates during sampling in each of eight consecutive years. I followed longer-term survivorship of these individuals marked as juveniles by sampling again 9 yr later, and developed conclusions as to how these data address the type of survivorship curve typical of

Sex-Biased Response of Raccoons (Procyon lotor) to Live Traps

-Heterogeneity of response to traps has important implications when interpreting mark-recapture data. We used radiotelemetry to investigate variations in recapture probability for adult raccoons (Procyon lotor) during live trapping conducted in S Texas from 1990-1992. Both sexes had higher recapture rates in winter/spring trapping periods than summer/autumn (males P < 0.001, females P < 0.001). Adult males were consistently captured more frequently than adult females in all trapping periods. There was a higher proportion of 'available' males captured while some females avoided capture. In addition to differences in movement patterns, intersexual behavioral differences in response to live traps were suggested.

Mark-release-recapture studies on three anthropophilic populations of Aedes (Stegomyia) simpsoni comple(Diptera: Culicidae) in Uganda

AbstractMultiple mark-release-recapture experiments were carried out on females of three anthropophilic populations of Aedes simpsoni (Theobald) complex at Nkokonjeru and Bwamba in Uganda to determine and compare the population size, survival rates and longevity of the adult stages. There were high recapture rates (26.23%, 2 7.42% and 28.28%) at the different sites. The population sizes, estimated by Jolly's stochastic method for the three sites (465, 561 and 675 female mosquitoes) were not significantly different, neither were the survival rates of the females (0.6026, 0.7145 and 0.8152). Other parameters estimated for the three populations were also similar. Population size estimates by Jolly's stochastic model and the simple Lincoln Index methods were not in agreement. The other method over-estimated population size. Since the estimated parameters for the Nkokonjeru population are similar to those of the Bwamba populations, there is a potential for the transmission of yellow fever virus to the human population at Nkokonjeru, as at Bwamba.

The effect of time, size and sex on recapture rates and yield after river releases of Salmo salar smolts

In each of the years 1988 and 1989, about 15 000 individually tagged Baltic salmon juveniles were released into the Umeälven (Ume river) in northern Sweden. Two release groups, sexually immature fish and previously mature males, of varying sizes were released at five different times during the natural period for seaward migration for Baltic salmon smolts in this area. Analyses of 1069 adult recoveries caught in the commercial sea fishery from 29 863 releases in 1988 and 1989 were undertaken. An average 7–8 times higher total recapture rate for releases of immature fish than releases of previously mature males was found, suggesting a post-release mortality related to the maturity type of fish after river release. In 1988, the highest recapture rates were obtained for immature fish (18.7%) and previously mature males (3.0%) released in late May. Larger fish had a higher recapture rate at all release dates. Fish released in 1989 showed about the same overall ratio in total recapture rate between immature fish and early mature males although the total number of recoveries was lower in 1989. The two maturity types of released fish had a similar growth pattern in the sea. Average weight at catch for releases of immature smolts and previously mature males was 4.0 kg. There was no relationship between early sexual maturation and grilsing (fish returning after 1 sea-winter). At optimal time of release (27 May), the yields (kg/1000 smolts released) from releases of immature smolts and previously mature males were 748 kg and 120 kg, respectively. This difference in yield between releases of the two maturity types of fish is suggested to be due to a low smolting rate among the previously mature males. If the ultimate goal of river stockings of Baltic salmon is a high survival to adulthood and a maximal yield, the proportion of early mature males in the stocking material has to be controlled. The annual loss in production value by releasing a large proportion of non-migratory previously mature males in Swedish rivers is suggested to be 400 tonnes having a present catch value of c. 16 million Swedish krona (at a salmon price of 40 Kr/kg). Alternative smolt management strategies are discussed.

Movement of tagged juvenile tailor (Pomatomus saltatrix) in Moreton Bay, Queensland

Large quantities of tailor, Pomatomus saltatrix, are caught by recreational and commercial fishers in coastal waters off New South Wales and Queensland. Juvenile tailor were subject to increasing fishing mortality in Moreton Bay (Queensland) in the mid 1980s. A tagging programme, involving State Government fisheries biologists and amateur fishing clubs, was established in 1986 to examine the movement, growth rate and fisheries exploitation of juvenile tailor (&lt;270 mm fork length) in Moreton Bay. Of 2173 juvenile tailor tagged in Moreton Bay during February-July and December 1987, 237 were recaptured over a period of 30 months, representing a recapture rate of 11%. This was a high recapture rate compared with those in similar finfish tagging studies carried out in Moreton Bay. The recaptured fish moved relatively short distances (mean�s.d., 10.2 � 15.0 km; maximum distance, 85 km). Growth data were unreliable. Estuaries such as Moreton Bay function as nursery areas for tailor prior to their movement onto open surf beaches as adult fish. A legal minimum length for tailor was introduced on the basis of this study.

Dispersal of phlebotomine sand flies (Diptera: Psychodidae) in a Colombian focus of Leishmania (Viannia) braziliensis.

Dispersal of five species of phlebotomine sand flies was studied in a coffee plantation near Arboledas, Colombia, by mark-release-recapture studies using fluorescent powders. The estimated recapture rate for males of Lutzomyia shannoni marked and released during the day was 28.1%, significantly higher than that for all other species (p < 0.05). Recapture rate of female Lu. shannoni was 9.5%, and no females of the other four species were recovered. This suggests either that Lu. shannoni is a more sedentary species than the others, or that the large trees on which these insects were captured and recaptured function as foci of lekking behaviour in males. The high recapture rates of females of this species may indicate that oviposition occurs in close proximity to the bases of these trees. Although most marked sand flies were recaptured within 200 m of their release point, a single female Lu. gomezi was recovered 960 m away 36 h after release. This suggests that the dispersal capacity of Lutzomyia species may be greater than has been thought, an important consideration in future control programs directed against these insects in Leishmania-endemic areas.

Management Briefs: Long-Term Retention of Anchor Tags and Internal Anchor Tags by Striped Bass

Abstract During 1984, 749 striped bass Morone saxatilis were captured, marked with both anchor (Dennison) and internal anchor tags, and released in the Hudson River. The difference in the relative retention rate between the anchor tag (42%) and the internal anchor tag (98%) was large during the first recapture year and became more pronounced during the second through sixth recapture years (2% and 98%, respectively). The longest that a fish with an anchor tag was at large was 908 d. In contrast, 21 fish with an internal anchor tag were at large for longer periods, as much as 2,127 d. These results show that when multiyear recaptures are desired for long-lived species, the internal anchor tag offers the potential for statistically higher recapture rates than does the anchor tag.

Recapture of pond- and hatchery-reared brown trout, Salmo trutta L., released in small streams

. Two groups of 0+ brown trout, Salmo trutta L., one pond-reared and one hatchery-reared (fish length 32-80mm), were released in eight small streams in three different areas of Norway between 1984 and 1987. Hatchery and pond fish were reared at different sites, but releases were made both near the rearing site and in the home area of the other group. A total of 2550 fish were recaptured by electrofishing the year after stocking. We found great variations in the recapture rates of pond and hatchery fish in one stream between years, and between streams in different areas the same year. These results indicate that the rearing method is not essential to the recapture rate. Both pond and hatchery fish generally had higher recapture rates in streams near their rearing site than in the distant areas. Thus factors associated with transportation seem to influence the survival of stocked fish. The results also indicate that size at stocking may be an important factor for the recapture rate.

Behavioural characteristics of the ayu, Plecoglossus altivelis, as predictive indices for stocking effectiveness in rivers.

A laboratory index to predict the stocking effctiveness of ayu, Plecoglossus altivelis, in a river was determined by comparing the results of a stocking experiment in a field and laboratory tests on (1) swimming ability, (2) optokinetic response, (3) & (4) tendency to swim upstream in artificial river-1 & -2, and (5) jumping activity to a waterfall. Fish groups used here were landlocked stock (LAKE), amphidromous stock (RIVER), and reared fish from three different hatcheries (HR-A, HR-B, HR-C). Stocking effectiveness represented by recapture rates through fishing season was positively re-lated with the tendency to migrate upstream after release. The tendency to migrate upstream in a river showed a close reiationship with jumping activity and tendency to swim upstream in artificial river-2, white it correlated negatively with swimming ability: i.e. Fish groups such as LAKE and HR-C with active jumping behaviour had a strong tendency to swim upstream in both artificial and natural rivers, resulting in a high recapture rate, whereas inactive fish in jumping behaviour such as HR-A showed a tendency to go downstream and thus, low recapture. It was concluded that both these two laboratory indices had the potential to predict stocking effectiveness of the ayu before release, however, the more appropriate index was the jumping test since the artifical river of large scale required much effort.

Influence of fish stocks on the recapture rate of ayu released in the River Tsubusa.

To estimate the influence of fish stocks on stocking effectiveness of the ayu, Plecoglossus altivelis, the dispersal patterns and recapture rates of wild and hatchery reared fish were determined through a stocking experiment in the River Tsubusa. During short-term dispersion just after release in May, two groups of hatchery fish (HR-A, HR-B) were mainly dispersed downstream, while wild fish (LAKE) swam upstream. However, another wild fish (ACCL) reared for 43 days before release had a lesser tendency to disperse than the others. Fish swimming upstream after release were larger in size for every group than those going downstream. During settlement and downstream migration periods (June-October), most recapture occurred in the area within ±2 km from the point of release. LAKE distributed more upsteram and HR-A, more downstream than the others. Recapture rate during fishing season was highest in LAKE (29.2%), and HR-B (5.9%), ACCL (1.3%) and HR-A (0.8%) following in order, indicating the superiority of the wild stock (LAKE) and a disagreeable effect of temporal rearing on stocking effectiveness of wild fish (ACCL). In conclusion, the stocking effectiveness represented by recapture rate depends on the dis-persal pattern after release: fish with stronger tendency to swim upstream resulted in higher re-capture rate, and are thus regarded as having a good fish quality.

Patterns of Residency and Movement Among Honeyeaters in Heathland near Sydney

We present patterns of residency and movement derived from the results of a five-year program of banding birds and a three- year program of observing the location and behaviour of individually colour-banded birds in heathland in Brisbane Water National Park, near Sydney. New Holland and White-cheeked Honeyeaters account for most birds captured or observed in our study area. We define a resident bird to be one that is observed nesting andlor is repeatedly sighted in about the same area over a period of at least two days and then categorise species on the basis of whether or not resident individuals are present throughout most of the year. Those species that satisfy the latter criterion also exhibit high recapture rates whereas other species have relatively low recapture rates. We argue that our definitions are more useful than others in the literature. Based on the above definition and on recapture data, most individual New Holland and White-cheeked Honeyeaters are either transients that are captured just once and are never mapped as resident; or occasional residents that are captured more than once, visit our study area throughout their lives but satisfy our definition of resident only some of the time. Future residents, for example, spend some of their time on our grids for an average of eight months before being mapped as residents. There are also gaps of about three to five months between periods of residency. During summer, the residents appear to spend less time in our study areas than during the rest of the year. However, there appears to be no regular, seasonal movement of New Holland and White-cheeked Honeyeaters into and out of our study area. Residents show little variation over time in the locations of their centres of activity in the heathland and do not move far from these areas. Consequently, emigration of resident birds is negligible and departures of residents must be due to mortality. This mortality of residents, which averages about 54% p.a., is associated with low availability of nectar, the principal source of energy to these birds. Individuals often change partners but not unless their partner vanishes, presumed dead.

Crab (Cancer pagurus) migrations in the English Channel

The development of the persistent suture tag has permitted the study of long-term migrations of large decapods like the European edible crab (Cancer pagurus L.). A tagging study of the growth and migrations of C. pagurus was part of a research project undertaken to provide advice on the effective management of the English Channel crab fishery. During the years 1968–74 a total of 15296 suture-tagged crabs was released; the majority in the main fishery off south Devon and Cornwall, but releases were also made in the eastern half of the Channel. The early releases were mainly inshore, within 22 km (12 nautical miles), but as the fishery expanded offshore releases were made in mid-Channel.Most of the recaptures occurred within two years of release, with the highest recapture rates being in the most intensively fished areas during the main fishing season. From the total of 2714 crabs recaptured, 2255 had reliable recapture information. In the inshore release areas 90 % of the males and 76 % of the females were recaptured within 18 km (10 nautical miles) of their release position. Offshore the corresponding proportions were considerably lower at 76 % and 59%, with 11 % of the males and 21 % of the females having moved &gt; 90 km (49 nautical miles).When males did move &gt; 18 km they were mainly the larger males and their mean displacements were 14–31 km in several directions. The offshore releases of males in the middle and eastern Channel showed more extensive movements, which appeared to be directed, most of them being in a westerly direction, with mean displacements of 41–114 km. With only one exception, the female inshore releases had a mean direction of movement of between south and west, with mean displacements of 12–84 km. Overall, those females making the more extensive movements were larger than those caught in the vicinity of the release positions. The last inshore release at Portland Bill gave the first indication of extensive westerly movements from the eastern part of the English Channel.Movements of females released on the offshore Devon and Cornwall grounds were mainly in a westwards direction, although several inshore movements and longer distance movements of up to 302 km towards the French coast were recorded. The recaptured females from the middle and eastern Channel releases showed greater mean displacements (110–158 km), all in a westerly direction. Only 10% of the mid-Channel recaptures were made within 18 km, with 73% being caught &gt; 90 km from their release position. The highest mean velocity was 23 km/week, with an individual maximum of 183 km/week.Most of the recaptures of male C. pagurus released inshore were made near the release position, and those movements which were observed would appear to be the result of nomadism. Offshore males seemed to be more mobile, but a nomadic existence for larger male C. pagurus seems more likely than migration. Female C. pagurus in the English Channel are more mobile than males. Large, mature, female crabs leave the eastern Channel and congregate in the autumn off south Devon. During the winter and spring there may be some nomadic movements. These migratory movements are reflected in the size composition and sex ratio. The migrations seem to be related to the breeding behaviour, ensuring a suitable sea-bed substrate for berried crabs and/or allowing distribution of the larval phase on the easterly residual currents in the English Channel.

Effects of Water Mite Parasitism on the Demographics of an Adult Population of Ischnura posita (Hagen) (Odonata: Coenagrionidae)

The demographics of an adult population of Ischnura posita (Hagen) (Odonata: Coenagrionidae) at a N Texas pond were studied using mark-recapture techniques. Twenty-three percent of marked females were recaptured vs. 20 percent of the males; the highest recapture rate was for mature females not parasitized by water mites. The average daily probability of survivorship ranged from 0.73 for mite-free mature females to 0.61 for mite-parasitized mature females. Water mites were present on one-half the population and were more frequent on males than females. The number of individuals displayed a marked peak during the study. This peak was coincident with the only observed cases of adult cannibalism. INTRODUCTION Ischnura posita is a small (body length: 18-29 mm) nearctic damselfly found throughout the eastern United States and Canada. It occurs in varied habitats including both lotic and lentic environments (Bick, 1957; Walker, 1953), and tends to be found at the margin of ponds and streams amidst dense emergent and peripheral vegetation. Unlike many adult damselflies, the aquatic environment does not serve it solely as a rendezvous site for copulation and oviposition, but as the ecological arena for virtually the entire life span of both sexes. Coenagrionid damselflies are often parasitized by water mites. These mites attach during the damselfly's nymphal stage and migrate from the exuvia to the adult during emergence. They attach primarily to the ventral surfaces of the insect's thorax and abdomen, and may often be found on an individual in extraordinary abundance. Utzeri (1980) reviewed reported cases of adult cannibalism in Zygoptera and suggested that it is the result of a situation where intraspecific communication fails. There is no published evidence indicating density-dependent adult cannibalism. STUDY SITE The study site is a 0.3-ha pond located in Veterans Park, Arlington, Texas. The pond is 127 m long by 36 m wide and has a mean depth of 1.6 m. It is surrounded by the following plant species: Eclipta alba, Juncus diffusissimus, Ambrosia trifida, Paspalum sp., Eleocharis sp. and scattered Salix sp. The dominant emergent plants are Typha sp. and Ludwigia peploides. The nearest aquatic site is approximately 0.4 km away and does not support a population of Ischnura posita. Ischnura posita was the most abundant zygopteran species present during the period of this study. Other zygopterans collected were Anomalagrion hastatum, Enallagma basidens, E. traviatum, Telobasis salva and Argia apicalis. METHODS Ischnura posita were collected daily from 21 May 1980 to 22 June 1980 (except 25 May). Individuals were uniquely marked on their wings with indelible ink immediately after capture and released near the point of their capture. Data regarding the individual's sex, its maturity and presence of mites were recorded. The presence of mites was determined visually without the aid of supplementary optics. The set of mite species was thus not completely determined. Samples of these mites indicate the presence of Hydrachna sp. Coloration was used to determine maturity of the damselflies.

The ecology of Aedes (Stegomyia) africanus (Theobald) in a tropical forest in Uganda: mark-release-recapture studies on a female adult population

Two mark-release-recapture experiments were carried out on a female population of A. africanus in the Zika Forest, in Uganda, to estimate density, survival rates, dispersal range and duration of the gonotrophic cycle. Marking was achieved using powdered fluorescent pigments and wet paint. In the first experiment, unfed A. africanus female mosquitoes were marked and released. A high overall recapture rate of 17.6% was recorded consisting mainly of first recaptures (up to 85.6%). The highest recapture rate was recorded during the first 4 days after release. Using Jolly’s Stochastic Model, daily population estimates ranged from 1386 to 8406 during the first 7 days of release. The daily average population estimated over the first 10 days was 3591. Using the Simple Lincoln Index, population estimates ranged from 1104 mosquitoes to 16,320 with an average daily estimate of 3706. Of interest was the fact that the average daily population estimates using the two methods were not statistically significant. The 24-hr survival rate averaged over 9 days was 0.9228. Dispersal was rather random, and appeared to be of a limited range with an average distance of 50 m. In the second experiment, which involved marking only fully engorged mosquitoes, an overall recapture rate of 7.1% was recorded, with an average daily survival rate of 0.8209 averaged over the first 4 days. The pattern of recaptures indicated a gonotrophic cycle of 5–6 days with a small proportion of mosquitoes seeking secondary feeds during the first 48 hr. It was generally observed that marking and handling did not have any marked effect on mosquitoes during the first 8 days.

マサバ太平洋系群成魚の移動

Two hundred and twenty-one tagging experiments were carried out during 1950 through 1968 on the Pacific Subpopulation of the Japanese common mackerel, Scomber japonicus. Tagged fish totaled 37, 025 of which 256 were recaptured (recapturerate being 0.69%). The highest recapture rate as related to type of tagging was reported for the Atkins type of tag fastened on to the caudal peduncle(1.35%). That for the ecological phase of the fish was for the spawning period (1.50%), and for geographical area it was for the Izu Shoto Islands region (1.37%), respectively. The recaptures after more than 100 days were observed mostly of fish tagged with the dart-type tag, thrust into the dorsum. Noteworthy exsamples were fish recovered 480 nautical miles away from the tagged place and those recaptured when the fish revisited the release site. The present observations may substantiate the hypothesis in regard to the movement and migratory patterns of adult mackerel of the Pacific Subpopulation.